Early version (SC) of the investment-cast Cinelli BB shell. No clue to the frame-builder but could help nail down the approx. year.
The detail that might be telling: that brake bridge (or rather "no-brake-bridge" if it's a track frame with no brakes), it looks like it has those little points that half-wrap around the stays. That was a signature detail of ------------sorry, can't remember his name.
Shoot a close-up of THAT and see if it rings a bell with somebody who CAN remember.