Building a seesaw with sliding seats
Step 2. Add base pieces [c] and [b2]
Pieces [c], 2x6 (150mm x 50mm): Cut 2 pieces @ 28" (710mm) long. Round the top cnrs.
Pieces [b2], 2x4 (100mm x 50mm): Cut 2 pieces @ 16" (407mm) long. Round or angle the top cnrs.
Fix base pieces [c] to pieces [b] and fix pieces [b2] to the upright pieces [a] with glue and screws. Pre drill the screw holes.
Refer to the pictures above and the dimension plans below.