Solder masks are layers of mataerial applied to circuitboards before soldering. The protect the conductive traces against oxidization and shorting out, but also help control the flow of solder when soldering the parts to the board. Solder masks are commonly silk-screened on to the etched circuit as a thin layer of coloured epoxy. Solder masks can also be lasercut from kapton films that have a hot-melt adhesive layer so that they can be ironed-on or laminated to the circuit baord. Another readily available way of making a soldermask is to lasercut or vinycut one from more common materials. It is important that the materials can withstand the heat of soldering, and fusible interfacing (hot-melt adhesives) can be applied to almost any flat material. Silk is a fabric that can withstand high temperatures and it also feels and looks nice.

Links:
Laser- and Vinylcut Solder Masks >> http://www.kobakant.at/DIY/?p=4909

Supplies

Kapton film
0.18mm thick SYNtherm(R) H from Snyflex >> http://www.synflex.com/

Kapton film with hot-melt-adhesive
CMC 70115 Kaptonklebeband mit Polysiloxankleber
Trägerstärke: 0.05mm
Gesamtstärke: 0.1mm

CMC 70968 Kaptonklebeband mit Polysiloxankleber
Trägerstärke: 0.075mm
Gesamtstärke: 0.11mm

from cmc Klebetechnik >> http://www.cmc.de

Kapton Tape
many online distributors

Copper Foil with Adhesive
Techsoft >> http://www.techsoft.co.uk/products/knife-cutting/materials/cutronic-foil-pcbs.asp