I need a hex/star wrench solution

[LBDamned]

You could probably rig something. Even some plucked foam would likely work with a little reshaping. I keep wrenches for my gas block, trigger and sight inside the grip along with a lens cloth, rag and OB tampon in case I get shot.

Needs a plug/cap/cover/plate though...

Stuffing into an opening with no closure - will fall out.

[LBDamned]

I run BCM grips mod1 I think. Has storage.

It does, and I've been considering it... I was on their site last night.

I'd rather use the BAD-AGT that i already have (multiples of) - but I think i might try the BCM.

[Barang]

I keep the relevant wrenches inside the pistol grip.

i have firing pin, ejector + spring, scope wrench in the pistol grip.

[dmcag69]

Here is a thought, right now, go through your Allen wrenches and stars and see which one is actually used for your equipment, scope, gun, rails, don't carry the extras, you don't have to carry spares for others at range also to borrow

Should be common cap screw for all
I second the pistol grip storage