Hacked travel-size (hardware) mouse + taxidermied (wetware) mouse = Mouse Mouse!
Fully functional, and furry!

Warning: this project involves taxidermy, dremels, and sometimes graphic pictures of dead animals. While there are no guts in this tutorial, viewer discretion is still advised. If you are offended by this entire idea, please peruse the wallet contest or the laser cutter contest instead.

Concept by noahw
Implemented by noahw and canida.

Step 1: Acquire Mice

Obtain a small travel-size (hardware) mouse. This one is a wired mouse that is way to small to use comfortably every day, but perfect for going inside of a mouse.

Obtain a similarly-sized (wetware) mouse. These are commonly available fresh or frozen from pet stores, or any other place that sells reptile food. It's easier to fit a small object into a large mouse than a large object into a small mouse, so err on the side of caution. You can always fill extra space with cotton balls.

If you've got an optical (hardware) mouse, make sure to choose a pale-furred (wetware) mouse for lightest skin pigment - this will be important later.

Step 2: Dissect (hardware) Mouse Part 1

Disassemble your mouse.

The mini travel mouse didn't come factory ready to get put inside of a taxidermied mouse. (What were they thinking?)

Thus, you'll need to take your mouse apart and see whats inside.

Take off the spring loaded cable retractor by taking out the screw and then pop the two halves apart with a screw driver.

Remove the little plastic nub that was on the wire so that the wire will thread smoothly through a hole in the (wetware) mouse.

Next, grab a marker and draw lines around all parts of the plastic mini mouse housing that aren't essential. We needed to slim our (hardware) mouse down to fit inside the (wetware) mouse. We used a rotary tool to remove sections from the front of the buttons and the rear sides so that the (hardware) mouse would fit between the (wetware) mouse's shoulders and hips.

Remove as much plastic as necessary to make your mice fit, but take care not to damage the circuit board. The pseudo-ergonomic styling is really for decoration- you can't make a little mouse like this ergonomic, so go ahead an trim it down to the size of the circuit board.

Make a new slot in the back of the (hardware) mouse for the cord- we need to relocate it to the back to fit with the (wetware) mouse tail.

Step 3: Dissect (hardware) Mouse Part 2

In order to pass the USB cord through the tail hole in the (wetware) mouse we had to remove it from the circuit board. This is done by desoldering the connections using a soldering iron. It's easy to do once you have done it before, so maybe practice the method a bit before you give it a shot on the actual mouse. For a quick explanation on desoldering check out the How to solder instructable.

Before you take things apart be sure to write down what wires go into what mounts on the circuit board so that you will be able to put things back together correctly.

Using a soldering iron, gently touch the tip of the iron to the ball of solder that holding the wire in place. After a second or two the solder will melt and the wire will come free. Leave the ball of solder attached to the circuit board - you can use it to re-attach the wires later on.

Step 4: Shave (wetware) Mouse

Grab a pair of tweezers, your fingernails, a razor, or some wax and remove some fur from your (wetware) mouse's belly. This is where the optical sensor will peek through at the end of the process, so you'll need to clear the fur out of the way.

We started with a sharp scalpel, then moved onto tweezers and fingernails as they are easier and less likely to damage the skin. Your mileage may vary- go with what works.

Step 5: Dissect (wetware) Mouse

Disassemble your mouse.

Take your mouse apart using the techniques described in my previous Mouse Taxidermy Instructable.

You should now have a bag of mouse skin; discard the innards. Remove the tail if you want to run a cord through the opening instead.

Wrap and wire the legs as described for a bit of support, but cut off the wire ends- we'll just let the legs hang loose around the Mouse Mouse body.

Prepare a head-only form, and attach the eyes.

Step 6: Assembly Part 1: Reconstitution

Run the cable through the tail hole, and re-solder the four wires onto the surface of the circuit board. Refer to the How to solder Instructable if you need a refresher on surface mount soldering. Once the wires are in place, plug it in to make sure everything works.

Reassemble the shell and circuit board, and hot-glue the pieces in place.

If you've trimmed any bulky edges of the casing away, you'll want to wrap them in plastic to keep the mouse skin away from the circuit board. We used folded-over kitchen plastic wrap, and hot-glued the edges to the sides of the casing.

Step 7: Assembly Part 2: Integration

I inserted the mouse head form just like in the Mouse Taxidermy Instructable, and trimmed the wires so they wouldn't interfere with the rest of the project.

We inserted the (hardware) mouse into the shoulders first, then pulled the tail region around the back. It was a tight fit - next time we'll find a fatter mouse, as it's easy to fill extra space with cotton balls! Skin is stretchy, though, so long as you keep it moist the mice should integrate nicely.

Sew up the back opening, starting near the tail and working towards the head. Leave a space for the scroll wheel- it won't work properly covered in fur!

Tack the skin down around the scroll wheel with a bit of superglue, taking care not to gum up either the buttons or the scroll wheel. I usually apply the glue with a tool, either a pin or a piece of wire with a small loop on the end.

Step 8: Optical Sensor

If you've got an albino (wetware) mouse, its skin might be clear enough for your optical mouse to work directly through the dry skin. Our mouse had a bit of pigment, so it was necessary to remove the skin flap. Thankfully we had already shaved this area, making the process much easier.

Make sure your completed Mouse Mouse is dry first, or the skin may pull and warp as it dries!

Use your X-Acto knife or scalpel to carefully trim a hole for the optical sensor to peek through, then add just a touch of cyanoacrylate (tissue glue, aka superglue) to the edges of the skin. This will toughen the skin edge and fasten it to the plastic around the sensor.

Use a tool (I used a bent piece of wire) to apply the glue, and do so sparingly- you don't want to drop any on the optical sensor!

Step 9: Completed Mouse Mouse!

Now plug your Mouse Mouse into your computer and test things out! Ours worked perfectly- I was really quite surprised by how well it turned out.

The buttons and scroll wheel worked beautifully, as did the cursor movement after we trimmed the belly skin away from the optical sensor. You may need to trim a bit of fur around the edges of the scroll wheel or optical sensor, but otherwise it's a wrap!

Keep in mind that this mouse isn't meant for heavy-duty computer use- it's a functional work of art, and should be saved for stylish installations and special occasions. Using the Mouse Mouse on a daily basis will likely cause shedding (the mouse) and RSI (your wrists), so we really can't advise it.

Of course, it's Really Damn Cool- every nerd who's any nerd should have one!