Layout Blocks System Hold Projects Secure!. Build your panel straight and square with these aluminum blocks and push pins. This bundle includes all of the Add-On Blocks plus push pins to handle virtually any size panel. Works great with the Homasote board. Includes push pins anThere are some options: 10 - 6"(40 push pins) four 3", four 12", two 17" and two 23" Add-On Blocks.