Step 4: Cut boards
Saw the 2x6 to the following lengths. Note: construction lumber is far from perfect. You're better off to buy too much lumber and cut out the worst bits (knots, damaged areas) - the offcuts are good for firewood, and you'll have a nicer loft bed.
Cut these 11 pieces with square ends:
5 x 400 mm, 5 x 486 mm,1 x 962 mm
Cut these 3 pieces with parallel ends at 14 degrees:
1 x 1900 mm, 2 x 1462 mm
Saw the 2x4 to the following lengths, all with square ends:
2 x 2032 mm, 1 x 1200 mm, 2 x 964 mm, 1 x 362 mm, 1 x 162 mm
Cut six pieces of 1/4" plywood to 250 x 486 mm, and cut some of the good 5/8" plywood into six strips 20 x 486 mm. Fill all the holes and imperfections in the lumber with wood filler, and sand. You're ready to assemble the frames.
Note: check these dimensions will fit your mattress! The design could accommodate a bigger mattress (double, queen, king) no problem, but you might like to use 2x6s in place of the 2x4s in the frame. Bonus: you'd get a much wider bookcase! There are slight design changes for the loft bed #2, but from here on I'll just describe the cloud bed (#1), for simplicity's sake. The construction is also exactly the same for both. Check the plans for the details.