Built my own mousecam this weekend.
The guts are a logitech 5500 1.3 megapixel video cam. It can also take 4 megapixel single shots too. Shoots video at 15 fps in HD 940 x 540 format.
The housing is an old trackball mouse. the hole for the ball is exactly the right size for a 35mm film canister which fits perfectly into the telescope. I can also mount the barlow and put the ratcam into that for even bigger magnification. Finally, the usb cable can go out the top where the mouse cable used to go... it's light, easy to use, gets perfect focus in primefocus mode.

Cool mod looking to build my own cam too, what software do you use