Well, despite
@Clio_fool reply being holy and legit, we do something similar.
I purchased a 3D printer to make prototypes to ship to people very far from Italy, to check fitment on their own car for new versions of spacers I never made, and of which I can’t find anyone else closer.
by the way, we don’t share any file. We act this way: inside EU, returning parts is so easy that we sell and if people don’t like, simply send back at his cost and get refund.
Outside EU, we go 3D first, or if people buy and then regret, ship at his cost and I do a full refund, less the Custom fee I have to pay when the part returns.
UK is outside EU.
I am a company, so I must make an invoice in any case, of which a buyer is going to pay a fee to the UK Customs. I don’t know the fre exactly.
Let me point out that it’s very rare that somebody regret and send the spaver back.