Saunders made a number of different "step & repeat" easels that are commonly available used. A paper carrier held a sheet of paper, and levers moved that carrier into different positions for multiple prints on a single sheet. Premier made a similar easel, and probably others did, too. The process (after you got the exposure figured out) was to print, shift, print, shift, etc. The Saunders had different covers so you could do 2-5x7's, 4-4x5's, 4-3x5's, or 8-2x3's on a single sheet of 8x10, or combinations thereof.

It's the easiest approach. I bought one a few years back on eBay for a bargain price. New, they cost several hundred dollars!

Charlie.