Pinning the deck beams

The holes are only 2 mm diameter and the length a little past the lower end of the tenon, marked with the masking tape on the drill.

The pins are bamboo barbecue skewers which you can buy anywhere like Wilko. They will not all be of the same width and I generally sift through the pack for the right fit. They are strong.

Excess tenon and pin will remain protruding.  They can be trimmed with a Japanese saw and chisel - best for finishing off.