This holder was inspired by others that are around, but that had the problem of not allocating USB sticks that are wider, including the SD adapter-reader.
This design allocates very well up to 8 USB wide sticks, and 8 SD cards of standard size, but only 5 micro-SD.
Also added holes to prevent from dust accumulation, and reduce a little the material used to print it.
* There is an improved version of this design available, try it here USB SD and MicroSD holder for wide USB sticks
Just print it in any infill density you want, it works well since 40%, or even less