cube([mainframemaxx+1, -mainframeminy, basethick]);
translate([-1, -rearwallthick, 0])
cube([mainframemaxx+1, rearwallthick, mainframemaxz]);
cube([mainframemaxx+1, -mainframeminy, basethick]);
translate([-1, -rearwallthick, 0])
cube([mainframemaxx+1, rearwallthick, mainframemaxz]);