I'm just thinking that building an actual rail and covering the table in speed cloth might be a substantial upgrade for the money I would be putting into it. Do you guys think its worth it? The material on the table now makes it pretty difficult to slide cards down the length of the table
The speedcloth (and new foam underneath, most likely required) would totally transform the table. Figure about $57 for the cloth, $23 for the foam, and $10 for incidentals (spray adhesive and staples).
Is it feasible to do the rail with a single piece of plywood? All of the plans ive been looking at seem to use 2 pieces from the original sheets to build to rail. I was thinking one piece cut then wrapped in foam then vinyl and secured to the existing table from below
You can certainly build a single-layer rail -- however, it will leave the outside edge of the table underneath exposed (presumably felt-covered), and it would need to be physically secured to prevent movement (not held in place by gravity, as can be done with an overhang rail).
You can secure it one of three ways: with industrial-grade velcro, screws from the bottom (make sure they don't go in any further than the wood), or with t-bolts installed in the rail prior to adding foam and vinyl.
It's the simplest and most cost-effective way of adding a decent rail to an existing table, or a cheap upgrade. Typically, you'll want your rail width to be 4" to 6" wide. Cost would include the 4'x8'x 1/2" plywood sheet ($22, unless already in-hand), plus $48 for foam, and $24-$60 for vinyl, and $15 for incidentals (spray adhesive, staples, and hardware).
Total refurb cost around $200 ($90 surface, $110 rail).