I purchased all materials for this DIY guitar support (except leather belt at a dollar store). Got the belt at a thrift shop.
A utility knife
One 2 - 2 1/2 " wide leather belt. 20-24 inches long
The leather should be a little stiff. The one shown here is braided. I did not use this one as you will see. Regular plain old, belt leather is best.
One piece of 1/8 " plastic sheet.
Enough to cut at least one 2" x 6" piece. I used a cheap "Betty Crocker" cutting board purchased for a dollar at a dollar store. Any plastic that is rigid yet can be cut with a box cutter will work.
Stick on velcro strips.
Strips come in packages of male/female pairs usually about 3/4" X 14" - 20"
2" diameter suctions cups.
These are often sold as holders with hooks. Just remove the hooks.
One 2" x 9" padded shoulder strap.
One side should be pebbled rubber or rubber. Strap must have some kind of "feed though" pocket for the belt.
$5 if you find an old pack or case in a thrift store. I borrowed one from my laptop case.
Total DIY Guitar Support Cost $10-$20.
It's quite possible to make your own guitar support for about $10 if you have a belt you can use or can get one from a friend, and if you forego the anti-slip pad or use one that you have on an old pack.
The cost of a similar store-bought supports ranges from $35 - 45 plus shipping. What's nice is that you choose the design and can customize to suit your needs using recycled material for 1/3 or less the cost.