Fitting brass eyelets

[Jurek]

Sewn in keder and keder rail could be the answer to your problem here.

[Neil C]

set of cheap wad punches (including 8mm)

https://www.ebay.co.uk/itm/6-PIECE-HOLLOW-PUNCH-SET-AMTECH-QUALITY-TOOL-LEATHER-HOLE-CUTTER-PAPER-NEW/324242381025?

£2.99 inc postage

cheers

Just noticed a set of punches is available at Aldi for the same price.
https://www.aldi.co.uk/ferrex-replaceable-punch-set-6-pack/p/704860419153801