Perforated Circuit Board, also called Solderable Breadboard. An acrylic board with holes drilled every 4mm spacing for electronic components. this is also about the minimum distance for spacing when sewing with conductive thread. Perfboards with copper line patterns are great for making small circuits and then sewing to them (by hand) with thread that is not too thick and does not fray too much. Though one can always cover the thread in fabric glue afterward.

Suppliers

All Electronics (California, USA) >> http://www.allelectronics.com/
Radio Shack (USA) >> http://www.radioshack.com/search/index.jsp?kwCatId=&kw=perfboard&origkw=perfboard&sr=1
Maplins (UK) >> http://www.maplin.co.uk/matrix-boards-47480