What about using a silicone outer layer shaped like a football approximately a quarter an inch thick. Then filling inside with smaller balls, silicone round balls, of perhaps the size of a cheerio or a airsoft bb.  The outer jacket would be for shape in the inside little BBS would hopefully defuse shock upon impact.

https://www.youtube.com/watch?v=7fwytA5r2Mw
recon you could do it with that stuff

yeah i had a idea like yours from that i was just worried if itd me like a bouncy ball when it hit and jump off somewhere but the shot inside might keep it from bouncing to much