I needed a present for my little sister's birthday earlier this month, and I was totally out of ideas. All I had was a cute little stuffed monkey, when I hit upon the idea to print a cage to put the monkey in. After printing everything out, I put him in with a little "Help me" sign, and he was sitting on a gift card. It went over great.

It was designed in OpenSCAD, and you should be able to tinker with it pretty well. With the exception of small fudge factors, the dimensions are all in the sizes.scad file. It may not work perfectly, as I got near my deadline I started using more fudge factors and experimentation.

The original design was to print the base and bars in one part (old_base.scad), but the bars were too wobbly so I stopped the print. Instead the whole design works like the roof was designed: the bars have little pegs on them that go in matching holes. The gate has tabs running down both sides that slide into specially slotted bars.

Because of the last minute design change, the roof and base are identical except for the cutout. If you want to mess with this I'd suggest making a function to handle it.

The cage is the biggest thing my Thing-o-Matic has ever made. I designed it to basically max out the build area.