The only time I would "willingly" use customers glass is when it is the old fashion hand blown glass, with all the waves, seeds, and other flaws vs todays modern float glass.
Ah!
A man after my own heart.
Just at this moment I'm re-fitting 6 large hunting engravings back into their original Victorian frames.
Five of them hold the original 'wobbly' glass and the effect is quite beautiful and harmonious.
The frames themselves needed some repairs but when I opened one up I noticed that the glazing had developed a scummy film on the inside, so all six had to be dismantled and cleaned.
The glass in one of the pictures had been replaced more recently with modern float and this just looked - bleugh..
Of course this is of no relevance to the question posed but the discussion had a certain serendipity to what I'm working at, at the moment.
Don't ask me what I'm charging. It's not enough but I'm just happy that someone still wants me to do anything.
Am lucky, no overheads, only Tesco's for food and I've already cut up my firewood.