Good suggestions, thanks- I've come close to both in my own thinking.

I do use reading glasses, and some of the cases are excellent in size and shape for this... the only really awkward part would be having the glasses case with me and still not having the glasses when I needed them. It even occurred to me that it might be possible to make a case with a less obvious pocket for a knife that also carries glasses- I do leatherwork.

I've also been toying with ideas for a "wallet" carrier of some sort... maybe a larger, flat carrier designed for a front pocket. Back would be a more convenient carry (I use front pockets a lot) but limit the practical size.