I understand you’re leaning towards a dowel for smaller diameter hinge assemblies.
But, did you consider taking inspiration from this iteration of likeablejerk’s entry of Design Challenge #1? Notice how the square axle sits in a square cut in the center of a circle. The axle-circle goes into a circle cut in the leg, allowing the throwing arm of the siege engine to rotate. It has the advantage of being all laser cut, without gluing and probably wouldn’t need any pieces on the end caps to keep the axle from shifting if the axle is a tight fit.