Long time, no updates. My computer shat itself fairly spectacularly about a month ago, so I haven't been able to check in until I got a new one up and running. I've been making slow progress anyway, I wasted nearly two weeks trying to build functioning hinges for the various crew hatches until I realised that I'd been working from two separate sets of measurements that were never going to reconcile and then gave up.
Instead, here are some pictures of the things that actually turned out alright!
Driver's hatch, rainguard, headlight and horn. The hatch and headlight are from the Tamiya KV-1 A sprue, with a reflector made out of 0.2 mm aluminium sheet and an SMD LED. The wires run through the conduit (1.5 mm stainless steel tubing) into the hull itself. The rainguard is brass that I heated over a flame and melted into position, so I'm hoping that it'll stay in place despite its fragility. The horn is scratchbuilt out of a 1/4" brass ferrule with some fine steel gauze bent into shape with the back end of a 6 mm drillbit. The bolts are styrene.
Periscopes in place, I ended up using the resin kit pieces after an embarrassingly rubbish attempt at making my own out of brass. I thinned the resin parts down and filled the bubbles with Mr Surfacer. I'm planning on hiding the signalling LEDs inside the periscopes with reflectors to make them visible from outside the tank, similar to how I hid them in my T-34/76's turret ventilator.
Scratchbuilt transmission hatches, the kit pieces were so thin they were translucent. You can nearly see through them! These are a bit more robust and have the characteristic flat spot, though I may have mis-measured and overdone them. I also added the coolant filler cap in the engine deck hatch.
Loader's hatches in place, just waiting on some functional hinges. They will need to be fairly strong since the tank's control deck lives underneath, which means they'll be getting a lot of use. I'll have another crack at fabricating them, and if that fails again I might need to look into these 3D printing shenanigans. Otherwise, more detailing!
This tank is coming out excellent! The details are off the charts. 
I happened to be searching the web yesterday and saw some very nice (small) brass hinges and hardware on eBay. These would be robust enough for you unless you want to attempt to build your own
