All - I wanted to alert you guys to something I found (maybe you already know about it and I am late to the party - not like that is new to me - lulz):
To wit - this revelation (if you could call it that, I suppose) of mine came after another user was posting about how to control Meccano's Meccanoid robot line using an Arduino:
A little research shows that the Meccanoid uses some custom "smart servos" to control it's joints - and to allow you to "program" the robot with custom moves - by moving those same joints! A bit more digging (ok - just clicking a link on that page) found this:
Everything you need to know to control and interface to these servos (and LEDs!) using your own microcontroller! Meccano generously provides this information (this shouldn't be a surprise - I wish all manufacturers would do this). It would be dead simple to write a library for the Arduino to control these servos (and read them!) - and LEDs.
The best part - look at this:
One of these servos retails (from Toys-R-Us) for $20.00 USD! Where else can you get a digital smart-servo, daisy chainable, bidirectional - for $20.00? NOWHERE.
If you wanted to build a humanoid bipedal robot - it is likely that you could grab a couple of the larger G15KS robot kits (they retail for about $180.00 each), plus a couple of those "expansion packs" - to get 18 servos. Add an Arduino Mega, an IMU module, maybe an ultrasonic sensor - and for around $500.00 you could build yourself a low-cost robot.
That said - I bet those servos wouldn't stand up to the strain for long - to get to that price-point, I doubt they are metal-geared, dual-ball bearing construction. But for $20.00, who cares?!
I wish I didn't have so many other back-burner projects - or I would be on this in a heartbeat. Since I can't, I thought I would put this out there, and maybe someone will be inspired to pick it up.
Edit: I just realized I made a mistake - the 8 servo robot isn't $180.00, but rather closer to $500.00 retail! Darn! Still - 18 of those servos alone would only cost $360.00, which is still very low cost. You would probably have to 3D print certain brackets (though they do come with some brackets that might work ok for part of the project)...