Soft material would be great, Minestorm let me know if you want the model tweaking to add in vents, some slots could be added however they would let light in so might need to experiment with angled slots.
Keep me in mind for when this awesome project is done! This is coming along so nicely. The rubber stripping made a big difference look wise and I can only imagine comfort wise too.
Noticed you said the rubber foam was costly. Have you seen the table and fireplace protector options at hardware stores? They seem like the same thing at a reasonable cost.