Not sure on the glass damage. The spiky glass balls bruised the victim through clothing but the setup was primarily to induce dodging into the pit so I wasn't worried about direct damage. We'll have to wait for the cage traps to net some subjects for experimentation. Depending on the found damage the Science! chamber will either be set up for executions or for danger room training.
The reasons that I won't be seeing the multi-stage pusher built yet are: we still need a water source, I don't think magma pressurises in the same way (and magma would bake the victims anyhow), we lack sufficient wood to build a big enough power station (until further trading is done). It'd be easy enough to setup an execution chute (especially as the great chasm goes from the lower cavern almost all the way up to the surface, but that's not as much fun. I'll do some sketches of my design idea though later on.
Oh, will floodgates stop a flying FB?
Hang on, would retracting bridges be a suitable way to control the fall? If so then I think I'll be able to rig up the multi-stage gobbo disposal unit
It'll just need a bit more manual control with the extra levers required. What's the most intuitive lever setup?
So more to add to the to-do list:
*Construct mini-Science! chamber
*Setup multi-stage retracting bridge goblin disposal unit
note: I should be able to resume DF in about a day and a half.