Here is an alternate much larger design, around 19.8L.
Designed to do literally any combination of possible parts.
The central rib can move left or right to either GPU or CPU side. This allows taller CPU coolers (130mm) with 2-slot GPUs, or 3-slot GPUs with a mid-height cooler (~80mm), or a 360mm AIO + 3-slot GPU.
Also allows mounting fans, SSD, HDD, radiators, or anything anywhere on flat plates. Last picture is an example with 3x 140mm fans.
I can't think of anything this design/configurablility can't do. It's like knex or legos for SFF PC building.
Down side is it is a ton of parts, a ridiculous amount of screws, and the price will be more in the $350 range vs the higher up design is $225.