I've spent many many hours in CAD with this issue
2 factors that play a part are the Boro tank not seated to the back enough, if you hold the boro tank down as you tighten it will fit with the filter without panel rattle, that aside the other factor was the battery wrap, I found different batteries affected the fit depending on the battery wraps, double wraps had no chance, the tolerance is so tight there's very little to play with on thickness.
My latest V203.2.1 panels (slight exaggeration) I ended up deepening the battery recess and also insetting the 1mm thick magnets by 0.5mm and found the sweet spot.
Problem is the corners have to be thicker to take the magnet so 2mm in the corners minimum, 3mm by the time I have resin coated them.
Now trying to perfect the fire button side, as you can see in this pic that the 1 side isn't sitting flush, this is proving to be a right twatter, slowly enlarging the recess but it's related to the circle so having a few breakthrough issues.
Since this photo I have manage to get the fit better with a dremmel skimming the inside cutout so back to CAD...