Features typeA ~ boards slide in from side. Tall ~ one lower slot for OBLS board ~ one upper slot for laser cut acrylic (or another board). Full ~ top frame border on four sides. Skel ~ material removed from bottom surface to reduce fabrication costs. Mounting wells for feet on bottom surface. Two mounting holes to secure bottom board. Slot height increased from 1.7 mm to 1.8 mm to increase process margin for different materials. Chamfer top window instead of radius. OBLS board is 3.65" long by 1.9" wide by 1/16" thick. Intended for User use case.