I offer semi permanent makeup, not EE, and a patch test is on offer (tho for me the result is inconclusive and I'm insured whether the client has one or not, tho the client signs a disclaimer that they waive the option). If a client wants a patch test and can't get in to see me at a good time, I can put some of the pigment in a seal-able mini pigment pot, and a lancet to scratch themselves, and pop it in the post to them. I don't know if the EE glue stays liquid in a tiny pigment pot, but if it does, this could be an option for the mobile ladies, to post out a sample and get a patch test thing then signed.