Background
I'm revisiting the idea of making a full size target. I've attempted it in the past, using foam mats, like yoga mats and foam tiles for toddlers' flooring. I ran out of material and the cost ballooned, so I tried using styrofoam for insulation as a base to glue on the rest... Results were definitely neither inconclusive nor positive.

But I'm back! In the meantime foam has just gotten even more expensive, and my archer at home needs a target for shooting an additional 500 arrows a week, for the few days we can't make it to the range.

Optimally we'd build a full sized target for 122cm faces, as my archer is shooting either 60 or 70m, depending on the mood.

Yoga mats and the like seem unlikely given the price. So I'm hunting for alternatives. And this is where I'd like to pick your brain.

I wanted to use straw, but was advised against it at the range. The common perception was that the straws are too abrasive or develope too much heat.

So here's my ideas so far, let me know what you think and if you've tried any of my ideas what your conclusions were:

• drop the idea of a full size target at home, and just shoot a bare mat at a couple of meters. I mean my archer still get 4 or 5 training sessions in each week, at full distance, so according to the coach it would be better than not training at home.
• various constructions where I fill some compartment with some loose material.
  • either in the shape of a bag, maybe made of tyvek. Maybe filled with blankets. That is what this seemed to be made of, when I examined it at the local shop https://www.hattila.com/en/cubes-and-blocks/6817-era-target-bag.html or shopping bags and other light plastic materials as suggested here https://www.wikihow.com/Make-an-Archery-Target
  • The bag filling material ideas, but in a wooden frame, with tyvek front and back. Maybe several layers of tyvek, so the filling material can be compressed.
  • Foam mattresses looks like they can be obtained for cheap used. But I don't think that the material can stop an arrow without ripping the spin wings off occasionally.
  • We have a small, 60x60cm, EVA foam mat. But it's too thin to stop the arrows. This mat could be reinforced with an a additional mat, at this size the price isn't astronomical, and placed in cutout in the center of a 120x120cm soft masonite board. I mean going below 8.5 avg per arrow is a bad end for this archer. So 9/10 of the arrows will be in the foam, and the last will be in the soft wood fiber board.
• Robbing a bank and buying an actual target /s

Edit(s): typo fixes