Richard,
Here are the details for the standard wood ammo crate for two artillary rounds. There are several standard sizes for several different munitions. I checked my box collection and this one is for 4.2 mortor but size is the same for 105MM Rounds. (No 105MM crates right now???)
Overall dimensions are 32" Long X 11 1/2" Wide X 7" High
Top and sides are 3/4" pine
Ends are 1" pine
Rope handles are 5/8" Diam
Ends are nailed thru handles and clinched on the inside.
This box would be the same for 105MM rounds with packing to fit on the inside.
The M84 HE M-1 round is 31.07" Long, 4.134" Diam and weights 42.07 Lbs.








Not too difficult to manufacture. You have the hard part to get. Over here we have crates but no guns. You have guns but no crates!
Let us know how the project turns out.
Cheers
Cat Man