Homebrew PCBs

Might I suggest autoclave steam tape from American Science & Surplus?

To Wit (from product description):

Steam Tape
Looks like ordinary masking tape, 1" wide x 60 yards, but made by 
Steris® Corp for use in autoclaves. Sticks tight, removes easily, 
is imbedded with cross-wise stripes that become visible when the 
steam temperature reaches 121°C (250°F), and permanent marker won't, 
they say, bleed or smear on it. Great stuff for medical or lab use, 
but also handy if you're repainting the sauna. (Or anything else. 
Looks just like everyday masking tape and costs less, despite it's 
hidden talents.) Made in the USA.

37665 STERIS TAPE $1.00 EACH (was $1.95)

http://www.sciplus.com/  (Search for steam tape)

The price sure beats Kapton from Digikey ($25.00 vs $1.00). I have tried it on a blank pcb with a heat gun and an IR thermometer. Brown hash marks appear at ~ 250 deg F. I ran the temperature to > 300 deg F and after the board cooled it peeled off cleanly and left no residue.

Baxter