I have built four of these frames. The first pictured I have been using for maybe a year or two and bought the clamps. The last three I have made I have built my own clamps with openbuild parts. I am still working on the design. At present I use wedges to apply pressure to the side of the wood and block. I am working on a cam system to apply pressure. I just bought 8mm screws with Knobs for quicker adjustment. I will update the build when I make these improvements.

an 8020 build with 1010 extrusion (1") Square tubing Rough size is 24x24x36 (600x600x900) The expected usable print area 21.5x21.5X32"roughly (510x510x760) An XY 3D printer with 3 extruders and 3 Z-axis 0.9 degree motors the table (Z-AXIS) will lift up to the XY Carriage on 3 12mm linear rod and 3 8mm Lead screw's Corexy designs complete and Z-axis build is started don’t have a 3D cad system yet so building my prototypes on a pcb layout tool