Parts list:
Tire Valve (2 per pack), PN 15-4559-2, = $6.49
5/16" Hose Barb 1/4" NPT, PN 15-5735, = $2.29
Ball Foot Air Chuck, 1/4" NPT, PN 15-503 = $6.49
Had on hand
Gas male 5/16" Quick Connect, = $3.50
Teflon Tape
2L plastic soda bottle
13/32" Drill bit
Parts:

Drill out the bottle cap with a 13/32" drill bit. This will give you a very tight fit. Punch the center of the cap with a nail, use a smaller bit to drill a pilot hole.

Trim the leftover plastic from the drilling with a sharp utility knife. Don't want plastic floaters in your beer.

Assemble the parts in the cap.

Put Teflon tape on the end of the house barb and put it on the Air Chuck. Put the male gas quick connect on the other end.

Connect the Air Chuck assembly to your CO2 tank

Use the Air Chuck to pump CO2 in to any soda bottle (1L, 2L,) just as you would put air in a tier. Adjust your CO2 pressure accordingly. Turn the bottle upside-down to check for leaks.
Basically built 2 of these for about $6 (minus the cost of the air chuck) vs paying $20+ for just one at the brew shop/online.
Not indenting to use this for "long" term storage, just to take beer with me without having to drag a keg and CO2 around.
Jason