I've used several types of surfaces with tops from various makers and the best of all (wrt spinning times) is also the cheapest: a mere 4$ 3x mirror. I don't think there is any risk of scratching the copper with it.
Thanks, I'll try it. I've seen tops that have been torn up by hard (e.g. 9H) glass, but hopefully the cheap glass of something like a vanity mirror will be soft enough. I'd much rather replace my spinning surfaces due to wear than replace my tops!
I totally agree. One more good thing of cheap mirrors is, they are much less brittle than very hard glass ones. I've been caught last year by the ForNeverSpin adds (my first and worst encounter with CNC tops) and their supposedly "Diamond-Like Carbon" Base had small scratches almost everywhere after only 2 weeks.