Homebrew PCBs

Reminds me of an idea I want to try someday.  Combine an aluminum plate,
soldering iron inserts, and a vaccuum pump - put the pcb and TT on the
plate, cover with something as if you were doing UV exposure, vacuum it
down to force it against the pcb (and the pcb against the plate), use
the soldering iron inserts in the plate to heat it appropriately, cool,
release the vaccuum.

Alternately - three layers.

Top -> lid, strong enough to withstand the vaccuum

Middle -> flexible plastic sheet that the TT paper is stuck to via
static cling or something.  Normally it would rest 0.1" or so above the
PCB.

Bottom -> aluminum plate with heating inserts and pcb.

At first, you apply vaccuum evenly to the top and bottom halves, so you
pump out all the air but don't press the TT to the pcb.  Then, you let
air back into the top, which presses the TT against the pcb,
guaranteeing no air bubbles (since the bottom half is still a vaccuum).
Then you heat and cool the plate to adhere it, then release the vaccuum.
In theory, perfect adhesion - correct temperature, even pressure, no air
bubbles.  Should work for UV film too, and you could mount the LEDs in
the cover to double as an exposure box.