Layout Blocks Hold Projects Secure A Delphi favorite Build your panel straight and square with these aluminum blocks and push pins. Adjusts to fit any size up to 16" x 26". 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 and four 3", four 12", two 17" and two 23" Add-On Blocks. Delphi Tip: Assemble Layout Blocks on Homasote Board.