This is an insert shelf that fits within the hex shelf available from The Range in the UK. However, if you have a hex shelf with an internal dimension of 186mm it should work for you (measured from one side to the opposite side).
The link of the shelf from The Range
You need to print 2 of the full hex inserts out (or 4 of the half inserts) and then print 4 of the joining arms.
I used an 8mm brim when printing so ensure it stuck to the bed correctly, however, you may need to use a raft.
Some minor sanding may be needed to get a snug fit within the shelf, and for the support arms to fit in the slots.
I glued my support arms in place to hold everything together more solidly. For the gap between the front panel and the back i used an Army Painter bottle laying on its side (25mm ish if you want to measure it out.
I use mine with The Army Painter paints and some 12 ml dropper bottles so any bottle between them sizes should fit fine. Vallejo, are a little tighter fit so a quick sanding of the openings would give the needed space.