I think I may have worked this out but I would love it if a real engineer could confirm it please? Is the fixing shown in the photos a shoulder rivet? Semi tubular? For the record the pictures show a collapsible music stand, the metal legs shown are both about 5mm thick and the fastener / rivet's diameter is approx 10mm on both visible ends. The two metal leg parts both freely pivot on this fastener so it’s essentially a hinge (bearing?) allowing the stand to fold up, but are also securely fixed together by it so there is no wiggle and it’s really sturdy, so it’s the perfect tightness.
I’m trying to prototype a similar part by hand so might struggle with a heavy duty machine rivet if that’s what it is, is there a locking / screwing equivalent I could try? Any other advice on securely fixing two movable flat leg parts is most appreciated.