Enclosures for my projects are a weak point for me. I thought I had the solution when I found a food container of suitable size, and self-adhesive plastic standoffs like this:

They go nicely into the corner mounting holes on the PCB. Alas the result leaves a bit to be desired as the translucency of the plastic decreases the contrast. It's not so bad when viewing from further away, but less than crystal clear. It would also look better at night with less ambient light. So I'll have to keep an eye out for a better solution in the long term and live with this interim solution for a while. At least I can recover the bench space to complete other projects.