Rar Box is Go!
In response to the occasional request for a “rar box” that can be installed in a costume or mask and provide sound effects:

I’ve had the parts for this for months but shelved it when I couldn’t get the damn thing working. Returned to it with a fresh perspective a couple days ago and got it sorted out.

This is not a voice changer; it can only play back prerecorded sounds. These are stored as WAV files on an SD or MMC card. In the example here I've got a different animal sound attached to each button on a keypad…but it’s very flexible in that regard, you could use magnetic switches in a glove to trigger different sounds, or pressure sensors in the feet to make stompy noises, things like that. Some limitations are that it can play only one sound at a time (it won't mix two or more sounds playing simultaneously) and the audio fidelity is not especially great (but not horrid either - see the demo, I think it’s more than adequate for rarsuit purposes).

It’s based on the Arduino microcontroller platform and the Adafruit Industries Wave Shield for audio playback, plus a few odds and ends. Not including the speakers, maybe about $65 worth of parts in total. The Wave Shield comes only as a DIY kit and requires soldering…nothing too heinous, anyone who knows which end of a soldering iron to hold could finish the task in an hour or so. If there’s sufficient interest I could assemble a batch of these for folks (with a suitable enclosure and whatnot) but would have to charge a fair bit extra for my time. Otherwise I’ll write up some directions and a bill of materials and folks could set about making their own.