1. width=210;
2. length=210;
3. height=250;
4. thickness=10;
5.  
6. //cube([width,length,height]);
7. cube([width,thickness,thickness]);
8. translate([0,(length-thickness),0])
9.     cube([width,thickness,thickness]);
10. translate([0,0,(height-thickness)]) {
11.     cube([width,thickness,thickness]);
12.     translate([0,(length-thickness),0])
13.         cube([width,thickness,thickness]);
14. };
15.  
16. cube([thickness,length,thickness]);
17. translate([(width-thickness),0,0])
18.     cube([thickness,length,thickness]);
19. translate([0,0,(height-thickness)]) {
20.     cube([thickness,length,thickness]);
21.     translate([(width-thickness),0,0])
22.         cube([thickness,length,thickness]);
23. };
24.  
25. cube([thickness,thickness,height]);
26. translate([(width-thickness),0,0])
27.     cube([thickness,thickness,height]);
28. translate([0,(length-thickness),0])
29.     cube([thickness,thickness,height]);
30. translate([(width-thickness),(length-thickness),0])
31.     cube([thickness,thickness,height]);
32.