I bought the 14pc Kobalt t-handle hex key set at Lowe's: Item #759896, Model #K14TH
The plastic "case" it came in didn't work for me. I prefer some kind of stand, certainly over the option of digging for the size I need in a toolbag.
Instead of buying a stand separately online, I started designing my own tool holders to print. I really only use the metric keys to work on 3d printers, so I didn't design stands for the SAE standard versions.
I realized some people may not have/need all the sizes, so I wanted to be able to print them separately, rather than one pieces with all 7 sizes. These are designed to be screwed into something as a base, such as a piece of wood or directly into a work bench. The holes are meant to be somewhat loose.
The (7) hex sizes in this set are: 2.5, 3, 4, 5, 6, 8 and 10mm. I would imagine these would work for any brand, so I guess they can be considered "universal", though, some have different length keys and handle heights.