(updated)
Printable gamepad written in Openscad for the N900 similar to the Game-Gripper. You can grab the code or view a screenshot of the latest 3D model downthread. This is the initial release, fIrst print is done and issues needing fixes are noted below. This first release is sized for N900s with the Mugen extended battery cover. I will measure for regular battery once this prints and is verified, probably tomorrow.
The V0.6 design needs a few tweaks like resized non-jam buttons, moved or removed USB port, tiny tweaks of two button peg holes, move the joining screw holes and enlarge.

Please post requests while I am still working directly on the project and you will have a better chance of getting a .stl model file made. I have only used the Nintendo64 emulator for Mario64 using the accelerometer for direction input, so advice from emulator power users would be appreciated. I am also open to other 3D project requests depending on available time and difficulty.

Now also featured on Thingiverse! http://www.thingiverse.com/thing:113285 You can grab the ready to print .stl files there.\

I don't see any N900 game grippers for sale anymore, it appears that Game Gripper still lists them but they have been on backorder and this is absolutely the only way double-Scud and Mugen battery users can get a working gamepad. This is not a game gripper but rather a clean slate printable model.

Ideally the available models would include source code, I chose openscad, so that it becomes easy to modify. As a fun gimmick maybe put the gcode for the current release into an app that can control a Mendel Prusa 3D printer via host mode so the new open-griper releases would appear on the repos, or perhaps a packaged native version of http://www.openscad.org/