Okay. I've got a basic robot frame. It currently has two wheels, skid plates in front, a pneumatic claw, and stall detection instead of bumpers.
Here's a picture of the front (taken without a flash). The gray plate in front is not actually used for anything, it's just there for strengthening. On the left side, you can see a red weight brick, which I have placed there to even out the weight distribution somewhat, so it rolls in a straighter line.
Picture of front, taken with flash.
The thing on the left below and between the two yellow plates is a partially-built pressure switch, which I will use with the compressor I plan to add.
The bot runs on two pairs of large wheels, and two skid plates in the front.
As you can see, I have already used up all of the RCX's inputs and outputs. This is likely to be a significant problem.
The pneumatic claw is currently mounted on the left wheel module, and has two motions: open/close and up/down. Due to a lack of the necessary pneumatic components, the up/down motion is non-functional.
I also do not yet have a small pump, so there is no compressor yet.
I have ordered a #9633 Dacta Pneumatics II set to get additional parts, including a compressor, air tank, switches, and T-joints.
Here's the motorized pneumatic switch for the claw, mounted on one of the vertical beams. The peg on the 12-stud black beam is pushed into one of the axle holes on the 40-tooth gear. The black friction peg is a stop to make sure the switch doesn't overshoot.
(See also the separate Pneumatic Switch page.)
Instead of bumpers, this bot uses stall detection through a rotation sensor on each wheel.
The NQC program consists of three files: Megabot.nqc, 2wd.nqh, and pswitch.nqh. Right now all it does is wander around, and move any objects it encounters with its claw. The object detection really needs improvement (it's too sensitive to ambient light).