Just about everyone I know who uses horseshoe nails for project layout has had at least one hammer disaster. Morton layout blocks make it easy to securely prepare your stained glass panels for soldering. They square up projects and provide great hold for your projects without horseshoe nail "dangers".
Use inexpensive soft board with your Layout Block System. Imitation plywood (such as "Homasote" ) and fiberboard panels (used in suspended ceilings) are two popular choices. I use free scraps of drywall left over from a remodeling project.
This add on set contains two 23" L shaped blocks and 16 push pins