maybe this ?

https://www.ajsutton.co.uk/product/y...00/rivet?uid=0

https://pt.fowlersparts.co.uk/parts/view/90269-07007

but you can get similar from Halfords. Check the hole size, by hand, with a 6mm drill bit.

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I have a lot of growing up to do. I realized that the other day inside my fort.