Parkour block 1000 × 1000 × 500, finger-jointed plywood

Timber-free version: six 18 mm plywood panels at the 1000 × 1000 × 500 outer size meet with box joints on all twelve edges: nine equal 111 mm cells along every 1000 mm edge and five equal 93 mm cells along each vertical edge, so fingers and gaps are all alike and symmetric, with the top and bottom owning the corners; every finger has a 2.5 mm pilot bore for a screw into the edge of the neighbouring panel (104 bores in total). Inside, two ribs cross at the centre in half-lap notches, one along the length and one across, so every wall is braced at mid-length; each rib carries four 120 mm tabs through slots in the top and bottom and two 100 mm tabs through slots in the walls at each end, with 0.2 mm slot clearance. The two-hand carry slots match the timber-framed block, with the lengthwise rib between them. The ribs slide into each other crosswise, the lengthwise one notched from the top and the crosswise one from the bottom; the exploded view in the viewer moves them up and down. The drawings show the ribs in teal. Estimated mass about 55 kg; the parts fit on three 1525 × 1525 mm sheets. Tabs and slots are nominal: a test cut on the actual plywood thickness is required.

The 2.5 mm pilot bores and the 130 × 45 mm carry slots are concepts, not certified lifting points. The cube's estimated mass is 221 kg: do not plan a four-person manual lift without a risk assessment and handle testing. Engineering analysis and full-scale testing are needed before children use these obstacles; cover the slots during use to prevent entrapment.