We were just contemplating when more momentum would be going for octagon shaped handguards and Strike Industries just released this shot of what they are calling the first heat sink AR with an octagonal shape and a seven-sided KeyMod System for mounting accessories. In addition to the top rail you would have four 45 degree angles for offset KeyMod accessories along with the three 90 degree angle mounts. Below is their 12" SI Mega Fins handguard with a 9mm AR, which they have designated as the first heat sink AR. We will be interested to see the final spec on weight compared to other KeyMod options on the market.
Strike Industries 9mm AR with 12" SI Mega Fins Handguard