Good work, looks like a decent build. Probably a fair bit better than the first crane I ever built (but I was young and dumb and that was 20+ years ago).
One question I'd have, does it still work (and balance) ok if you tilt the tripod head (which would subsequently tilt the camera sled)? If so, that would give you nice tilt control of the camera... which would be especially useful, since I personally probably rarely do crane moves with the camera absolutely perfectly horizontal. Could also put a small head on the camera end to give you a lot more freedom... for a camera as small as a DSLR I think the rig could handle the weight of a smallish head... it looks to be built robust enough.
Fantastic Plastic Entertainment, Inc. fantasticplastic.com
It's possible to unlock the head to tilt the vertical harms and so, the camera. With a quite strong tripod with counterweights it's OK, but as the main axis of the crane is above the tilt axis of the tripod head, this might quickly result in a heavy weight on the front or rear. I think mounting a small head on the crane could be a nice improvement, it's definitely robust enough.