How is best to present photos on a budget for a small exhibition?

Hi!

I run a small business where I digitise film, slides etc.

I have a recent client where I scanned glass slides from we think around the 1940’s that show how where we live used to look.

It was a really cool project and he now wants to do an exhibition of the scans I did and he wants me to put together the pieces for him, but its not like an exhibition to sell the images, just a non-profit display for the public.

I was wondering what the best way to present them would be in your opinion? He’s not got the largest budget (he is getting funding hopefully but a large amount will be from his pocket from the sounds of it- although that could change)

He discussed getting them on canvases but these can be expensive, I have experience mounting images on foam boards etc and framing images, but I just want an opinion on what people think is best!

Thank you!