As Jim, in N.C. says, making your own is easy enough. I've made a number of them to sand the various curved pieces (especially rockers), I've made over the years. I like using a 2X4 (11.5" long) for my beltsander belt.... my hand fits a full 2X4, better than a 1" thick board does.

Speaking of another sander, my PC orbital sander's foam pad has deteriorated and fallen apart. I removed the decay and installed a felt pad. The felt pad is the same as the felt caster material, used on the bottom of furniture feet/legs. The large rectangle felt pad was trimmed to fit the sander's disc and, with the sticky back, attached to the disc nice & firm. I used (my upholstery) foam spray adhesive to attach the rubber sheet (that the sandpaper adheres to) to the felt. I think felt should work fine, as a replacement pad. The pad's replacement cost range from $15 to $25, plus shipping, on Amazon. The felt costs about $5 for a 2 rectangle pack, at Walmart.

Sonny