Ideas to cover oriented strand board...because it is ugly.

I could not agree more. For the difference in price I use plywood or dimensional lumber every time, but you have what you have. Things that don't go the way you would like are opportunities. The challenge is yours to come up with a solution to take advantage of the situation. I know, that's why you are here.

You could veneer them, but at the cost of veneer, tools, and adhesives you would be better of replacing them. Only real choice I see is several coats of paint. Using a flat paint, irregularities of the board will be less obvious, but semi-gloss tends to be more scrubbable.

Shelf paper, Contact paper, or that spongy plastic mesh shelf covering will go a long way toward hiding the surface where you place the contents on the shelf. Adhesive paper, like Contact, will not adhere to the raw OSB. You'll have to paint first.

I've never seen fabric covering shelves but I don't see why you couldn't spray adhesive and wrap the shelf in something from the bargain section at Joanne's. I'd spend some time perusing Amazon or other sites for shelf coverings. Never know what may inspire.

I covered my dark wood cabinet shelves with white laminate sheets from Lowe's cut to size and glued it down. You could use a marble or granite or another color to suit your taste. I wouldn't use contact paper. (BTW- i got my 4x8 sheets hugely discounted because they had like 3" chips on one corner each).

My cost of 2 sheets of laminate and glue was about $60. I did it to my many kitchen cabinets.

Contact

Contact paper, wrap it all the way around, start at the back. EJL.

Contact paper would be super easy, and there are *so* many options according to your taste!