Over CNY spring cleaning, we dug up a dead cellphone and promptly gutted it.  There’s a pretty nifty vibrator motor inside:

Doesn’t this look like a carapace?

A small clothespeg was turned into a battery holder.  First, disassemble the clothespeg, and cut out two grooves:

Glue a short piece of wire into the groove, and make a little paperclip-like bend at the end.  Then reassemble the clip.  The springy bendy ends will pinch a little button cell nicely (instant battery holder!)

Wire it up to the motor, and superglue the whole thing to the back of the shell:

Add a few more wires for decoration, then clip on a battery:

A little vibroroach!