For animatronic bang for buck you cant beat radio control servos. Especially the cheap clone ones you find on ebay. They're small and very strong.
Arduino is a pretty good way to control them as there is a servo library available. Be aware that the arduino you have sets a limit on the number of servos (and which pins) you can control.
Good luck, miss you!
Nice stuff, but rather pricey. I would expect CERN to have huge quantities of this stuff in use, they may well have a pile
of offcuts you can scrounge.
Something to consider as a beefed up version of lego mindstorm are aluminium build kits; the name of which I can't remember at the moment. Essentially aluminium bars with a serifed 'X' cross-section that you can then use bolts to attach to; they're really useful for fast prototyping frames and similar. Somewhere on thingiverse there are files for 3D-printing them as well (another useful addition maybe?)
That is a 10mm mini version, a bit too small for many things but ideal for prototyping something that will be made from
the bigger stuff (typically 44mm).
It is a bit cheaper from here, at least until shipping is added:
More to the point, they sell the individual bits to restock the starter kit for when you make something you want to keep.