Carbon mouse

Introduction

If you are tired of getting your finger cramped clawing a small standard mouse, you may find this project interesting.

Spending a lot of time at my computer, I started noticing fatigue of the index finger and wrist at the end of the day. So one day I decided I had to do something about it and started looking for a good mouse. My enthusiasm just lasted the time it took to discover the price tags of a real ergonomic mice like the Handshoe. So I decided to make my own mouse.

I took inspiration from this great project by Hey Jude: Ergo Mouse, but my work is considerably different in design and method. The shape is loosely inspired to aFunc MS-3, but differs on the inclination the hand has when holding it. The techniques I employed in the making are different enough to justify this project. Instead of shaping the styrofoam, I made a fiberglass mould, which I used to make a carbon fiber (and fiberglass) mouse.

This instructions are just a guideline, as most of the stuff I experimented with in this project was new to me too. Hence, there actually is a lot of room for improvement.

For example, I used carbon fiber because of its pleasing appearance, but I did NOT employ a correct technique! You are warned that if you follow my example you will never get perfectly bubble free piece of carbon fiber. But you'll have something that looks almost just as good.

Before you start

This project requires some experience with soldering, as we will have to solder on printed circuit, which is pretty difficult.

You will also have to use resins, carbon fiber and fiberglass, which is not hard but may require a degree of dexterity.

It will also take a lot of time!

If this discourages you, you may want to reconsider the available retail mouse.
Try to measure the distance between the tip of your thumb and the tip of your pinky, the distance between your wrist and the tip of your middle finger, and the width of your palm under the notches. These measurements should help you get an estimate of how large/long your ideal mouse should be. Consider the kind of grip which better suits you and try the mouses on display in the stores.

Here I collected the dimensions (metric) of some commercial mouses.

I was very much inclined to buy the Func MS-3, but in the end I preferred the DIY way.

My mouse

Is in fact a fat rat, being over 12 cm wide and over 16 cm long.

Is virtually indestructible.

Has cheap standard switches and sensor (800 dpi).

Fits my hand very well. It holds my thumb higher than normal, causing my wrist to rotate about 30°, which I find soothing.

Has adjustable weight, but you have to open it up first.

Was never meant to be beautiful or perfect.

I am content with it.

Step 1: What you'll need

Bill of materials

• light/thin fiberglass: 1 m^2
• heavy fiberglass (about 3mm thick): 0.5 m^2
• carbon fiber cloth: 30x30cm should be enough
• release wax (polyvinyl alcohol also works)
• epoxy resin. It is important that it is transparent! I used this one (search for one in your area).
• clay or DAS or PU foam for the model
• gypsum filler/stucco/putty and/or epoxy filler
• acrylic spray varnish
• 1 working mouse
• wires from cat5 or usb cable
• about 6 tiny flat-head screws (i used M3x8)about 6 tiny elongated bolts (i used the pc standard - those that hold the motherboard)
• Teflon feet (which you can grab from other mouses or buy)
• heavy M8 or M10 bolt and screws OR some stones
• baking paper
• optional: stickers or aluminum tape
• optional: gypsum powder for the mould + gel coat (you'll need less fiberglass in this eventuality)

Tools

• soldering iron
• multitool (dremel) with sanding and grinding abilities
• hot melt handgun
• sandpaper P280, P330, P600 (or similar fine grits)
• screwdriver
• cheap brushes
• cutter
• scissors
• permanent marker
• (pencil) lead

Step 2: Kill a mouse

1. take a mouse with a sensor good enough for you. I used a cheap optical mouse with an 800 dpi sensor, which is fine for me
2. disassemble it completely. You will need the pcb and the switches on it, the plastic lens, the wheel, the Teflon feet, the cable it has it. It is also better to take the lens housing on the platform and the stands supporting the wheel: cut the plastic neatly (don't use hot blades) to get the pieces you need.
3. usually retail mouses have a steep down-slope on the front buttons, so that they can employ a single pcb for both buttons' switches, wheel and sensor. It's unlikely you will achieve the same efficiency. My design is very different, so I know I need separate these three elements:

a. study the electric lines and look where you can take advantage of the thicker lines (easier to solder on)
b. write down all the connections in order of line and/or pin number on the main chip. For example if you know that the first line you see is the middle click action and it goes to pin 7 on the chip, take a note of it.
c. remove the two switches of the buttons.
d. cut the pcb where it hurts the less, using a thin saw.

Step 3: Resuscitate it

Now we have to get the electronics back to work.

Follow your notes to figure out what goes where, and prepare some wires. I used a usb cable. Keep the wires long, so that later you can comfortably open the mouse if needed. IMPORTANT: take note of the color of wire you will use for each function. The buttons in particular.

Scrap the plastic surface of the pcb to get to the copper, put some tin on it, then solder the wire. Finally secure it with a drop of hot glue.

As you can see I put my switches on a piece of breadboard just to check that everything works. It does!

Step 4: The model

I lost many picture of this first stage of the work as I had a problem with my pc and didn't make a backup. I'm sorry

The first thing to do is to shape a model of your ideal mouse.

Do that in your mind. Then try some mouses at the mall and think again about the design you want/need.

Then you can proceed with the creative part.

Use a material which is easy to model (and stands the heat). I used PU foam, but that is not the ideal choice. Maybe something like clay or DAS would be better. I also tried a cheap gypsum (plaster): don't even bother, that went very badly (but ironically, I got a picture).

Anyway, if you go with the PU foam, you'll easily carve out the shape in a few minutes, but than you'll have a very rough, porous surface, scattered with holes. To fix that you can use a stucco: if you use gypsum stucco it will be easy to polish, but it might stick on your mould. I you use an epoxy stucco (putty) you'll have an hard time to get a nice result, and you'll also have to wait longer, but there is no risk of it ruining the mould.

I suggest you do a simple shape, DO NOT mark the buttons on the model. I did that and it caused me a lot of troubles later, and It was completely useless.

Step 5: The fiberglass mould

If you have the gel coat, you can also make a gypsum mould. It is cheaper and faster. Google how to. I didn't want to buy the gel coat, so...

1. Paint the model with the wax and let dry.
2. Now cut your fiberglass in triangles and squares.
3. Prepare the resin and mix it thoroughly.
4. lay the lighter fiberglass cloth on the model and brush some resin on it. Do NOT swipe the brush, but tap the fiberglass repeatedly until it soaks well.
   BE VERY CAREFUL NOT TO LEAVE ANY AIR BUBBLE!
5. When you have covered the entire model, lay another layer of thin cloth, and then a layer of the thick fiberglass. That should suffice, but if you think you might do further changes to the mould later, then add another thick layer. This way you will be able to grind and carve the mould happily without fearing of making an hole in it.
6. Let polymerize until completely hardened and dry. My resin took 24h.
7. 5. Remove the model. It may help to blow compressed air between the mould and the model. If it does not detach, destroy the model.

Step 6: Refining the mould

If the mould is not smooth and presents air bubble cavities, fill them up with stucco. I used a cheap gypsum stucco, but at this point it would be better to use epoxy. Polish.

Now it's time to take in consideration the mouse buttons. I wanted 2, and I think the best way is to have them cut directly in the mouse shell, like two peninsulas (cut on three sides). They have to be quite long (about the size of the index finger), in order to be flexible.
You have two options to make them: either you keep a simple cast and then cut the buttons and the necessary holes in the hard fiberglass, or you contour the buttons directly in the mould. I chose the latter.

1. design a shape for your mouse buttons.
2. Use a cutter to precisely cut some plastic (I used PP approx 0.8mm thick from food packaging) and superglue these splinters on the mould, so to shape the outline of the mouse buttons. I used pieces of plastic about 7mm high.
   Remember to also make the hole for the wheel.

Step 7: The cast

I know this isn't the proper way to use carbon fiber.. but this easy method works. The use of an oven is actually optional, and making a vacuum on such a complex shape is a little too difficult, isn't it? There are some tiny tiny bubbles in the resin, yes, but the result looks acceptable to me.

1. First, coat the mould with the wax and let dry.
2. In the meantime, cut the carbon fiber cloth and the thin fiberglass in convenient shapes for your mouse.
   Please note that the carbon fiber cloth is more flexyble and ductile than fiberglass, because the cloth can shift and be made a little slanted.
   It's really hard to cut carbon fiber without making a mess of it. To get better results than I did, I suggest you put a thin strip of transparent tape in the back of the cloth, and then cut in the middle of the strip. This way the cloth won't disintegrate, but it will be harder to bend it!
3. Prepare and stir the resin.
4. Put your pieces of carbon fiber in the mould and soak it with resin. Possibly make two layers of carbon, then proceed with the thin fiberglass: add another 2 or 3 layers. Add 4 layers if you did not shape the buttons in the mould.
   Tap each layer with the brush, and BE VERY CAREFUL NOT TO LEAVE ANY AIR BUBBLE!
5. cover with baking paper and press out the air towards the outline
6. Let polymerize until completely hardened.
7. detach from the mould
8. clean from any residue of wax

Step 8: First improvements

1. clean the cast, cut the excess fiberglass/carbonfiber
2. If you still are without buttons, cut them out carefully with the dremel saw for plastic. If you already have them, clean out the excesses so that they can move smoothly. Grind underneath the buttons to make them more flexible. Proceed with care, so to make them as light as you like. Take another mouse for reference.
3. grind/sand the outskirt (?) of the mouse to make it as flat as you can. I found this very difficult!! it helps to mark with a marker pen how deep you should grind in any point.
4. cut a little hole for the cable (if you're making a cable mouse) in the front of the mouse. I used a small mill.
5. cut to pieces of plastic (I used the carcass of the old mouse) to make a bar to click on the switches.
6. hotglue said pieces into place. Try to keep them parallel to the plane on which you think your switches will lay.

Electronics meddling

this could also be done in the end, but it's better to do it now:

1. cut two pieces of matrix board suitable for holding your switches in place.
2. solder the switches. In order to improve the order I connected the first board to the second, bridging the grounding, thus leaving me with just 3 wires to be connected, all to the same board. Mark the point to solder with colors corresponding to your wires and the notes you took.
3. hot glue the boards into place. You should now be able to click the buttons

Step 9: The platform

1. Put your half mouse on a sheet of paper and draw its outline.
2. cut two sheets of thin fiberglass and 2 thick accordingly to the shape. Cut out the space to fit the lens housing, near the center of your mouse.
3. start with a thin layer and soak it in resin as usual, then add two thick layers and finally a thin one.
4. cover it all with baking paper and press out the air bubbles and excess resin
5. let harden
6. remove the excess. You have two options: either you hide the platform inside the mouse, or you can put the mouse on top of the platform. I think the first method gives you a prettier result, and I chose it. The other way though is way easier to do.
   If you chose to hide the platform, then you have to sand/grind its outline to make it smaller until it fits in the mouse. As you must proceed by trial and error, this is incredibly difficult and you should use extra care. Maybe there's a better way to do it, some technique I don't know.

Step 10: Soulmates

1. when mouse and platform matches, drill some flared holes along the perimeter of the latter.
2. insert the flat-head screws and screw the bolts
3. put mouse and platform back together and check that the bolts fit. If they don't, cut off the screw on the top
4. when everything fits, remove the screws.
5. I used a lead to mark the position of the holes on the "wall" of the mouse
6. screw back one bolt on the platform, and then drop some hot glue on the corresponding marked spot. Put back the plate and wait for the hot glue to stick to the bolt. Unscrew and remove the platform. You should have the first bold fixed. Reinforce with more glue. If something goes wrong don't worry: just melt the glue and try again.
7. repeat for all the bolts.

Step 11: Polishing

1. remove the backplate
2. sand the mouse with light sending paper and water to remove any imperfection. I used P280 and P330 grits, but it would be better to finish with even finer sandpapers. Be careful not to remove too much. I do not advise to use the dremel polishing wheel.
3. clean and dry it
4. if you want you can apply some stickers. I cut some shapes from aluminum tape.
5. spray it with transparent acrylic varnish. Spray from a distance of at least 20cm, slowly. You don't want any drop to coalesce.
6. follow the instruction on the spray can for applying a second coat. Apply at least 2 coatings.
7. let it dry completely 24h

Step 12: Putting it all together

1. fix the lens housing and the pcb into place on the platform with some hot glue.Make sure there's no dust on the lens and sensor!
2. solder the wires to the button boards.
3. fix the wheel pcb and the wheel stand with abundant hot glue. You can fix them under your button switches or on the platform (in this case you'll have to try until you find the right position. Draw some marks as reference)
4. if you need more strength cut some strips of plastic from something (I would suggest food packaging) and glue them in position to support the wheel
5. make a knot on the usb cable and position it on it's little hole. You can glue that too!
6. add some weight, to your preference. You can use steel bolts or even stones. Fix those on the platform with, you guessed it, hot glue.
7. optionally, you can put some dark tape around the buttons, without preventing the movement. This should help keep the dust out
8. close the whole thing
9. stick the Teflon feet on the bottom
10. plug it in and enjoy!!