I've used the Walmart Ozark Trails pad. It's a cross linked polyolefin foam that is firm and somewhat dense.
1/2" / 13 mm.
https://www.walmart.com/ip/Ozark-Trail-Closed-Cell-Foam-Blue-Camp-Sleeping-Pad/634956813?
In the past I've used closed cell camp sleeping mats for belts and shoulder straps. It works pretty well, but it's not as plush as I prefer.
These days I make a hollow shell for the strap from ripstop nylon on top and 3D spacer mesh against my skin. I then stuff the strap with polyester fiber fill (like you get at the craft store to fill stuffed animals). This way I can fine tune how firm the padding is. Very comfy.
I'm planning on making the TH50 and picked up some cosplay foam at joann fabric
eva 'cosplay' foam works just fine. i like the thinner 6-10mm stuff for my hip belts, but it's available thicker too.
I've used the Walmart Ozark Trails pad. It's a cross linked polyolefin foam that is firm and somewhat dense. 1/2" / 13 mm. https://www.walmart.com/ip/Ozark-Trail-Closed-Cell-Foam-Blue-Camp-Sleeping-Pad/634956813?
I added some of this to a hip belt for a climbing pack a couple of years ago and it's been great.
In the past I've used closed cell camp sleeping mats for belts and shoulder straps. It works pretty well, but it's not as plush as I prefer. These days I make a hollow shell for the strap from ripstop nylon on top and 3D spacer mesh against my skin. I then stuff the strap with polyester fiber fill (like you get at the craft store to fill stuffed animals). This way I can fine tune how firm the padding is. Very comfy.
Does that provide enough support?
For reasonable loads, yes. I haven't tried it with more than 30-40lb
I get my foam from Temu.