I work at a curtain shop. When you sew coated fabric drops together to make blackout curtains, there will be little pinpricks of light visible along the seam lines. It can't be helped; this is what happens when you stick a needle through the lightproof coating.
We regularly have people ask if we can do something about the pinpricks. Answer: Sorry, no. These people are generally understanding, and the question is fair enough because we used
to be able to do something about it - we used to be able to order jars of the liquid coating and paint it along the seams to fill in the holes. (It was a pain and a half and took more time and effort than it was worth, and now it's really hard to find the liquid coating anyway, so file that under Things We Don't Do Any More.)
For the real Harry Potter moment, though, we had one customer ask if we could make a seam go away. The showroom staff thought she was asking about the pinpricks of light, and started explaining, only to have her interrupt and say no, no, she meant could we make a multiple-drop curtain without seams
. As in, she thought we could somehow fuse or graft the pieces of fabric together so that you couldn't tell it had been joined.
Nice showroom staff:
...No. Thaaaat's not possible.
Strange Lady: Oh. *pout*