4Game

https://i.imgur.com/o4w0eVi.png

Another option that's only slightly harder to get but yields 152 slots and a bunch of 2×2 blocks:

https://i.imgur.com/Hu2adlv.png

I made a simple info-graphic of one of the many configurations that can be used to expand an item case. Item cases take up 16 slots and have 64 slot capacity and can be expanded up to 144 slots using stuff that's easy to find in raid or on the flea market.

You can definitely get a larger effective capacity by nesting other cases in the item case (like ammo boxes or weapon cases) but I believe this is the most we can get with rigs or bags. The is useful since cases are restricted and early game when we don't have access to T H I C C stuff this is an easy way to condense the pile of rigs you have in your stash.

For example, I use the configuration shown to store all my scopes, sights, and small attachments!

I hope this is useful for someone.

Edit: /u/Dzy23 added below that you can use a sprut from a shotgun to store three attachments in one slot too. This way you can condense your flashlights and lasers.

Edit 2: Alternatives to spruts appear to be the following handguards which can hold more lights, a scope and foregrip:

• Trax 1+Trax 2+Trax bridge rail
• AK 5.45 Design Aggressor handguard
• AKS-74U CAA XRSU47SU tactical handguard
• AK TDI X47 tactical handguard rail system

You can slim down your 2×1 scopes by putting them on a LaRue LT101 QD Tactical Picatinny Riser mount too!