Step 5. Smoothen poles 1 to 12 by scraping the surface using either a bolo or a bamboo scraper. Then mark the spots where you will drill holes for the dowels.

Step 6. Using a bench drill with a hole saw (this is a metal cylinder with toothed edges), drill 4 cm-wide holes 4 inches away form the edges of poles 1 to 12. If you don’t have a bench drill, use a hand drill instead. Make sure to use the correct drill bit so the holes would be of the same size. But the holes of poles 3 and 4 must run through. Aside from the holes of poles 8 and 9, you must also make slots. Pole 9 must have three slots on the right if the holes are facing the floor; on the other hand, pole 8 must have six slots, three on its left and another 3 on its top when the holes are facing the floor.

Step 7. Pole 12 should also have three slots that are in line with the top slots of pole 8. to make the slots, drill about an inch at the middle of each pole and another one about 5 inches away on both sides of the middle slot. Then drill two more holes on poles 5 and 6; these holes should be 1.5 inches away form each other. For poles 10 and 11, drill a hole about the size of pole 12 an inch away from the edge.
The whole process above is called the boring phase.