The shoe one costing less than $2 holds 4 Rhinos (could put one more in) in various methods including 2x2 facing or like this with two long and two flipped the other way.
The next size up, holds a flyer nicely, just add padding. Just $4!
The next one (a sweater box) holds 4 of the standard GW trays, the first one goes in with a slight bow but when all 4 are in, you can add a foam topper on top and everything is snug and secure! Not bad for $6.
Side shot to see how everything packs in nicely.