Step 1: Procure Mice
You'll need some dead mice.
These came frozen from the East Bay Vivarium. Most pet stores will happily sell you pet or feeder mice, but they may not exhibit such nice color variation. They may also be alive; if so, you'll need to be able to fix that yourself or find another supplier. Choose wisely.
Mice can be stored in ziplock baggies in your freezer until you need them. Don't repeatedly freeze/thaw your mouse or leave it in the fridge for an extended period as this decreases the skin/hair quality. An hour or so at room temperature is usually sufficient to thaw your mouse.
Step 2: Assemble Tools
You will need:
plastic to cover your work surface (a trash bag does nicely)
beads (for eyeball replacement)
fine scissors (nail scissors are OK)
scalpel (X-Acto knife is OK)
fine-gauge wire (I've got 26 gauge)
thicker wire (mine's not marked, but is probably 12-15 gauge.)
thread (close to fur color is preferable)
Step 3: Cut Wires
Cut the following:
4 x 9" thin (26 gauge) wire
1 x 12" thin (26 gauge) wire
1 x 16" thicker (~15 gauge) wire
Note that the lengths may vary a bit due to the size of your mouse.
Step 4: Make Voodoo Doll- Cotton Balls
Make the 'voodoo doll' you'll use to stuff your mouse.
I find that making a properly-proportioned voodoo doo the hardest part of this whole procedure, and am working on a personalized fool-proof technique. The dissection is the easy fun part, but then I spent years in mouse labs doing gross and microdissection, so your mileage may vary.
At any rate, the voodoo doll requires three things:
your mouse (for sizing)
the thick piece of wire, bent in half
Start at the crimped end of the wire to make the head. Add 2 - 3 (partial cotton balls are OK) balls and squish them into the crimped wire. Compress them firmly, and measure the package against the mouse's head. They should roughly match the nose to neck distance on your mouse as shown below. Keep the balls pinched tightly and twist the wires several times to hold the cotton balls in place and create a bendable neck joint.
Add 6-12 additional cotton balls to make the rest of the body. Line them up in a row, compressing them tightly, and again match them against the mouse's body. Keep the wire squeezed in along the sides to prevent the cotton ball stack from folding over and popping out. Twist the tail ends of the wire tightly, keeping the cotton balls pinched, to create at least 1/2 inch of twisted wire. Clip the wire off and use the needle nose pliers to fold the sharp end over and into the cotton balls.
Step 5: Make Voodoo Doll- Wrap Thread
Now we'll apply radial compression to keep the voodoo doll properly dense.
Wrap the end of the string around the 'neck' between the doll's cotton ball segments to tack it down, then begin wrapping the body.
Make a couple of longitudinal loops down and around the tail end of the doll to round the tail area, with neck wraps in between for stability. Then make lots of wraps around the body to properly compress the torso. Add a couple more loops lengthwise as necessary. When the body is properly mummified, make a couple of neck wraps before moving to the head.
Make a couple of longitudinal loops up around the nose and back to the neck, with neck wraps in between for stability. Then make lots of tight wraps around the head to for compression, trying to form an elegantly tapered roughly conic snout. Check your mouse for rough proportions.
Double check that your voodoo doll is tightly mummified, and wrap or tie the thread off around the doll's neck.
I find making the voodoo doll to be the hardest part of taxidermy, and really need to spend more time practicing and perfecting my dolls. These are decent, but nothing to write home about.
Step 6: Make the Voodoo Doll- Eyes
Finally we need to add the eyes.
This requires a couple of mouse-eye-sized cheap plastic beads. Black works well for all mice, though you can choose to use eerie translucent red for a realistic albino look. The beads below are a bit big, making for some rather surprised looking mice. Next time I'll get some smaller ones.
Thread your needle, doubling back the thread and knotting both ends together. The double thickness of thread will help keep your mouse's eyes from rolling unexpectedly.
Make a couple of passes through the head to set the thread, then come out where you want to place the first eye. This can be determined by carefully aligning your mouse with the voodoo doll, checking relative eye position on the head. Pass the needle through the bead (make sure you've got a thin enough needle!) and back into the doll's head very close to the original exit point. Bring your needle through and out the other side of the head. Take another stitch to increase stability, then bring your needle out under the bead again and repeat the step. Make another stabilizing stitch, compare your doll to the mouse again for reference, and attach the other eye in the same fashion.
Make at least another 3-5 stabilizing stitches, then cut your thread.
Step 7: Initial Incision
This requires the scalpel and of course a mouse. If you're going to be wearing gloves put them on now.
Make an incision along the mouse's spine from the shoulders to the hips. You'll be able to see the difference between skin and muscle tissue pretty clearly, and the skin will be very loosely attached. Make sure you've cut all the way through the skin so you have a nice space to work with.
Dump a pinch of the Borax/cornmeal mixture into the incision, and we'll move to the next step.
Step 8: Peel Skin
Insert your fingers under the skin around the mouse's torso to separate the skin from the body. This should be quite easy to do; just tryl not to punch through the abdominal wall into the stomach/guts area to avoid stinky smells. Sprinkle the Borax/cornmeal mixture into the nooks and crannies as you go.
The original incision will propagate if you pull too much on the skin, so keep an eye on it. You may need to hold the end of the cut to prevent it from tearing too much further when working in the area.
Liberate the torso, then we'll go to work on the legs and tail.
Step 9: Hind Legs
Once you've worked around the torso, start on the hind legs. Carefully peel the skin back like a sock, being careful not to pull too hard. The skin will peel back to the ankle.
Now you'll need scissors to cut the leg off at the hip joint. The two leg bones will remain attached to the foot and pelt for use later when we wire up the limbs.
Repeat with the other hind foot.
Step 10: Tail
Now that you've removed the hind legs you're on to the tail.
First you've got to carefully detach any other bits of connective tissue (for the elimination and reproductive systems) joining the body and the skin near the tail. Don't worry about this too much; just slowly work your way up from the stomach, gently but firmly pulling the skin away from the body. You can do this with your fingers (pinching at the skin and at the body before pulling) or with scissors.
Now the tail is the only hind-end connection between the body and pelt. The tail is basically a long skinny sock covering a long thin bony tail. When you get the knack of it, removing the tail skin is quick and easy. Roll the pelt back to gain good access to the tail, then hold at the folded edge of the tail skin and directly adjacent on the denuded tail. Carefully pull these two points apart, again gently but firmly. The tail may try to turn inside out like a sock; it this happens no worries, just don't let it go so far that you lose the tail tip within the roll or you'll get to have LOTS of fun turning it right-side out. Readjust your grip as necessary so your fingers are very close to each other when you pull the skin from the tail. If the skin turns inside-out you can pull it back on (like a sock, remember?) and re-pinch to include the loose skin.
At some point the tail skin should just pop loose and come off intact. When it happens you'll know.
Sorry about the lack of action shots; you'll have to imagine this one until I get the time to stuff another mouse. In the meantime, here's a picture of the tail sans fur.
Step 11: Forelegs to Head
Carefully work the skin down around the forelegs just like you did on the hind legs, then clip at the shoulder to remove the legs from the body. The forelegs will also remain attached to the pelt for later wiring.
Pull the skin up past the neck towards the head. The next point of attachment is the ears, which we'll take up next.
Step 12: Ears
The ears are attached to the head. Now that you've pulled the skin all the way up to the ears (check on the outside of the pelt to make sure you're actually looking at the right spot!) you need to detach them.
First scoot around under the skin all the way around the ears with your (closed) scissors, identifying the junction point. Now cut through that junction. You can use your scissors or, for more control, use the scalpel to cut from the front to the back parallel to the skull.
Now peel the skin a bit farther forward, stopping when you reach the eyes.
Sorry, the best picture I can give you is post-ear-detachment. You can see the remaining ear canal, though. It'll be pretty obvious when you're actually looking at your mouse.
Step 13: Eyes
Using the scalpel, carefully cut through the connective tissue attaching the eyelids to the skull. You want to make sure to leave the eyelids attached to the pelt, so take periodic peeks at the exterior of your mouse to make sure you're doing it right.
Lots of small, slow, and careful cuts will release the eyelids quite easily.
Now pull the skin foreward until you reach the muzzle, as shown in the final picture below.
Step 14: Nose
Use your scalpel to detach a bit more of the skin from your mouse's muzzle, but stop short of the actual nose.
Work around the lower jaw with the scalpel to detach the lips, so that the only remaining point of attachment is the nose itself.
Use your tweezers to break the bones just behind the nose, then lift the broken fragments out taking the skin with them. These remaining fragments should now be easy to remove from the skin.
Step 15: Clean the Pelt
Now you should be holding an inside-out mouse pelt.
Remove any remaining bits of flesh or fat stuck to the skin; rub with the cornmeal/borax mixture if necessary to sand off any heavily-stuck bits. Don't stress too hard about getting every last bit, just make sure there are no big chunks left.
Remove the flesh from the arm and leg bones. Your scissors and/or scalpel can be used for this task. Again, don't stress about getting every little bit off; just make sure all the big stuff is gone.
Step 16: Invert and Moisten
Now that you've cleaned up the pelt, flip it back right-side-out and make sure all of the bits look right.
Run a moistened finger around the inside of the pelt against the skin to keep it moist for further handling. If it gets too dry you'll have a hard time getting it around your voodoo doll properly, and may lose some fur. The more frequently you skin mice the faster it'll be, and the less you'll need to re-moisten the skin.
Step 17: Wire the Legs
Now find your four pieces of thin wire and a cotton ball.
Unroll the cotton ball, and wrap some of the wispy bits around a leg to simulate the flesh you previously cut off. Be careful not to overstuff, as the leg needs to fit back inside of same skin it came from.
Now take a wire piece, and put one end up against the cut-off end of the leg. Run the wire straight down towards the wrist/ankle to make a brace, then make a U-bend and wrap it around the leg, cotton, and brace on your way back up. Crimp the U-bend just enough to make sure it'll fit into the wrist skin, but be careful not to break the delicate bones.
Leave the long piece of wire poking out for later use.
Repeat this process with the other three legs.
Step 18: Insert Voodoo Doll: Head
Make sure the interior of the head is properly moist, then align the voodoo doll's bead eyes and insert it into the head skin.
Wiggle it in slowly, using your fingers and the tweezers as needed, and scoot the eye holes over the eye beads. Once you've got this part situated, the rest of the head should fall into place relatively easily. Scoot the pelt back around until the head and neck are properly situated. Keep the wires out of the way for now.
The mouth will gape open to show cotton at this point, but we'll fix it later.
Step 19: Attach Forelegs
Now we're going to wire on the forelegs.
Make sure the head is properly situated and the legs are fully pushed back into the skin, then push the arms as far forward as they easily go.
Holding the arms in place with one hand, twist the wires in place on the voodoo doll's back, centered just below where the shoulder blades would be. Next carry the wire ends down under the doll's belly for another few twists, then up to the back again for a final stabilizing few twists. Viewed from the side, the wire should zigzag up from the paws to the back, down to the belly, then up to the back. This provides a stable armature for your mouse's poseable arms.
Twist the ends of the wire a bit more, then clip it off and tuck the ends into the body of the voodoo doll to avoid damaging the pelt.
Step 20: Insert the Tail
Now that you've got the front half of the body taken care of, we'll insert the tail.
Fold the rest of the pelt forward, exposing the rest of the back opening and the tail.
Carefully insert the wire/cotton twist into the tail, and run it as far along as possible. Don't worry if it doesn't go all the way to the tip, and don't force it- you don't want to tear or poke a hole in the tail. It's very easy to accidentally insert the tail wire through the rectum, but you'll know immediately if you've got the wrong hole. Try again for the tail, and do it right this time.
Remove any extra cotton and twists left past the end of your mouse's tail, and spread the two pieces of wire wide.
Step 21: Attach the Tail
Flip the back half of the pelt back into place along the voodoo doll, and position the tail where it should be after the mouse is fully stuffed and sewed.
Much like the forelegs, you'll be holding the tail in place while pulling the wires around the body and twisting them together. Make a nice long twist on this one, because instead of looping around the doll's body for stability we're going to tuck the wires into the pre-existing body wires from the forelegs. Cut the wires and tuck under, making sure no sharp ends are exposed to damage the pelt.
Step 22: Attach Hind Legs
Use your fingers and tweezers to scoot the rest of the skin around up and over the voodoo doll's rear end and position the hind legs.
This is much like the forelegs and the tail: get them where you want them, at full extension, then pull the wires around the back and twist them together. Make a long twist, cut off the extra wires, then stick the twist under the nice tight wiring from the forelegs. Make sure not to leave pointy bits sticking up anywhere along the mouse's back.
Step 23: Sew Closed
Now that you've got all the limbs wired and the fur pulled into place, stitch the back opening shut.
Use doubled thread with a big knot tied at the end. Stitch back and forth between the two sides of the opening, bringing the needle up under the skin then out, over, and up under the skin on the opposite side. The technique is really like lacing up your shoes.
Stitch from the neck down to the tail, fluffing the fur as necessary to keep it from getting caught up in the thread. The thread should basically disappearinto the fur, though you can use a matching color to avoid problems.
When you've successfully closed the opening, make a knot just above the fur surface, and poke the needle back through the slight gap at the end of the sewn line and into the cotton balls; it can come out through the pelt most anywhere. Tug it through until you hear the knot pop inside the cottonballs. Cut the string near the end of the fur, then tug the pelt until the tail end fo the string is pulled back inside. This should be sufficient to hold your stitches in place.
Step 24: Pose Your Mouse
The most stable position for your mouse is likely to be sitting upright, using both hind legs and the tail for support. You should make sure you can get this to work before trying more complicated poses.
Bend the arms, legs, and tail using the wire support to keep the pose. Wiggle as necessary.
Step 25: Pin Feet and Mouth
Put a pin through the footpad of the hind feet to keep them from curling up as they dry.
Keep the mouth in place with three pins: one to hold the lower lip up, then one to hold each of the bifurcated upper lips down over the bottom lip. Sewing pins work just fine for this.
Now clean up- roll all of the nasty bits up in your plastic table covering, place into a plastic bag, and tie it off. Add it to a trash can that will be emptied sooner rather than later. Wash your hands to get rid of any residual Borax, and you're done.
Step 26: Let Them Dry
Leave your mouse to dry for a day or two, depending on your room's humidity. Keep it out of direct sunlight.
Check periodically to make sure the extremeties aren't drying inappropriately. Use your fingers to fluff the ears (they tend to crinkle), the forepaws (they tend to curl), or the tip of the tail (if the cotton doesn't completely fill it), and check the mouth (pins can fall out).
The fur is probably all manky-looking after the rough handling you've given your mouse, but this is easily fixed with a toothbrush and some water. This also helps to remove any residual blood, Borax, or other suspect gunk from your mouse's fur. Good grooming is key to a smart-looking mouse. (These below are yet ungroomed.)
If you want to make costumes for your mice, you should probably do this BEFORE they're all dry and crunchy, since you may want to maneuver them to properly fit the costumes. They can still be sewed in afterwards, but you'll have to make any adjustments ot the costume instead of the mouse. More instructables on this subject later.
Step 27: Remove Pins and Display
When your mice are dry, pull the pins out and put your creations on display. Remember making dioramas in elementary school? Well... they're waaaay better with mice.
They make great wedding cake-toppers as well, if you've got friends with the right sense of humor. Kids love them, at least if they're young enough to ignore parents' concepts of disgust. Pets generally ignore them.
Photo credit: thanks to Jess for the fantastic photos. Check out her first mouse, pictured in the comments.
Teacher credit: thanks to Jeannie who teaches an awesome mouse taxidermy class at Paxton Gate in SF.