I am doing a craft/quilt show in Sept. and would like some ideas
on how to keep my bolts of fabric standing upward for people to see. The first show I did had a wall that I could use for a brace to hold them up but this one will only have the curtains on all 3 sides. Any ideas on what to use? Thanks.

Not tested but just a thought. I would try heavy book ends.

Lay two 2x4's out like railroad tracks. Attach
pvc pipes upright on the 2x4's spaced evenly. Both 2x4's will be identical. The pvc probably should be 1/2 the height of your bolts. Put one bolt between each set of two pipes. This makes the bolts at a right angle to the 2x4's and 2 pvc pipes between each bolt. (1 pvc pipe on the 2x4 in front and 1 pvc on the 2x4 in the back) When you are looking at the fabric bolts from the front, head on, you would see a pvc pipe, a bolt of fabric, a pvc pipe, a bolt of fabric, a pvc pipe, etc. and the wood would be underneath. Cut the 2x4's into whatever is an easily transportable length. I hope this is easy to understand.

Instead of stacking the bolts upright vertically, how about laying them down side-by-side on the table. That way you won't have to worry about them falling over and people can still see each fabric individually. I make a beeline to anywhere I see fabric, whether it's up, down, or stacked so I don't think you'll have a problem attracting customers, I personally can spot a bolt end a mile away.

Then you could use anything with a little weight to hold the ends, a couple of bricks, a block of wood, those old metal bookends you see in offices with the lip on the bottom that goes under the books would work really good.

Thank you for your great ideas. This is just my second show and I'm brainstorming for different things to try.