Hi, I've just made my first cold smoke generator, It won't be the last, but as a first step it works ok so far. It's a bit flimsy and I have plans afoot to make another, more robust one.
I used two A10 'food' tins that the son got from work, luckily one had a slightly smaller diameter, so the two fitted nicely. I drilled the top one and installed the 'T' piece and fitted an 'End' piece to one end, after drilling a hole in the centre to accept the thinner diameter tube. The thinner tube extended 1" past the centre of the 'T' piece and out through the other end. I made a jacket out of a bit of wood to keep the tube central and sealed it with a bit of modelers clay. Then fitted some plastic aquarium tube to it, the other end fitted to an 85 litre per hour pump.
I fitted some clear hose to the output end so I could 'hide' the smoke around the side of the shed / greenhouse. (5ft length)
I half filled the lower can with wood dust and a few chips and lit it. Nothing happened!
I removed the 5ft hose and drilled 5 or 6 'air' holes around the base - something I had forgotten to do!
Re lit it and got about 10 minuets of grey / blue smoke, then it went out.
I decided I needed more air, so I borrowed the sons 12v tyre inflater, very noisy but OK for a test. I re lit it and obtained a more or less constant stream of grey / blue smoke, left it running for an hour, I would have left it longer but the noise was deafening.
I got there in the end, more or less. A new quieter pump is on order.
The outside / ambient temp was 60°f the temp at the copper outlet end was 81°f I plan to put a 'cooler' unit on the outlet to see if I can lower the temp some, this may need a better pump, as I think the length of your pipe is connected to how hard you blow.
I now need to fit out my 220 ltr food grade drum, then hopefully I can start smoking!!