Our scissor lift from last year was very light and extremely simple. We gave it one function and planned on using it once per game. If you choose to do something similar for stacking tetras, pneumatics may be out of the question because recharging air will take 30-60 seconds. Before each match last year, we precharged using a compressor that we attached to our cart. Pics of it can be found in the Chiefdelphi pictures section under 2004 robots and 2004 Canadian Regional. Also at firstrobotics.net - our website is going reconstruction and has no pics of last year's bot.
[edit]
Just posted some pictures from last year:
http://www.chiefdelphi.com/forums/pi...gle&picid=9411
http://www.chiefdelphi.com/forums/pi...gle&picid=9412
Hope they're useful.
[/edit]