If you've got a few basic tools and some spare time you can make this for a few bucks
Step 1: Tools and Supply List
Wood saw. Power or not depending on how much work you want to do
Phillips head screwdriver
3- 3/4 inch x 4 inch solid wood pcs at least 21 inches long each for uprights and base
2- 3/4 x 4 solid wood pcs. For the jaws
I- 2x4 about 4 inches for center post
11- 2 inch wood screws
6- 1-1/4 inch wood screws
1- 3.5 inch bolt
1 T-Nut ? Insert nut ? matching size to bolt.
Enough leather or heavy vinyl to cover the heads.
Step 2: Rambling a Little
I designed this for the height I felt comfortable at sewing in my truck bed, picnic tables and in my office chair or any sitting position, it's mid chest high and is not meant to be a tabletop version, I've used it standing up on the table with ankle weights holding it in place and it was stable but a little short. it fits under my legs and with rounded edges I barely feel it at all.
I guess the most important part of the whole thing is that every connection point must be square. If not the jaws won't grip your project correctly.
Step 3: Preparing the Uprights
I then used thumb tacks to hold a piece of chrome tan in place. I changed that later into contact cement but couldn't get to the inner part without taking it all apart so I left the inner tacks in place. You need this leather here to prevent marring your project.
I measured down somewhere I didn't think would be in the way on most of my projects, about 10 inches and drilled an appropriate sized hole for the t- nut insert nut. I wanted it flush so my thread wouldn't get caught on it. Thread gets caught on everything. Why add one more hook somewhere. On the opposite side I used a washer to stop the bolt head from getting stuck in the hole. I changed that later to that square looking washer thingy to help tighten projects. Not needed though. Just squeeze the 2 pcs of wood together with your hand to cinch it down then Tighten the bolt by hand.
Step 4: The Base
Then i made pilot holes in the uprights appropriate with the center block and I screwed the uprights into the center block with my screws on the right side slightly offset from the screws on the left side so they couldn't connect inside the center block.
I used a razor knife and shaved all of my base and upright sharp edges to save sanding time then sanded those areas smooth for more a comfortable overall use of this thing and I was done.
No I wasn't.
So when I started using it I quickly realized that my perfect fitting uprights that fit perfect on the top were way too tight when I put something in there. My top biting edge was being pushed out at an angle and I wasn't getting an even grip on my projects and the whole thing was putting way too much pressure on my projects. I then took the uprights off and put 2 washers on each screw. This gave me somewhere between 3/16 and 1/4 inch total spacing up top and I let the adjuster bolt do the job it was intended to do.
It's ugly as hell but using junk pile wood and hardware from the odd n ends box the only thing it costed was time.
Thank you for Checking out my stuff.
I'm not a carpenter I'm more like a wood butcher, but I'll try to make something I need from scraps before I pay full price for it.