It was actually really simple if you use PrusaSlicer.
1. download prusaslicer
2. download the MagHex doors from thingiverse.
3. load a MagHex door into prusa slicer.
4. on the left side is an option that allows you to slice a model, just chop off the bottom of the door making sure to ‘keep top part’, getting rid of the bottom hex.
5. right click on your newly chopped down door and scroll down to ’add part’, then ‘from file…’
6. add your talisman sabre floor hex of choice
7. move the hex to 0,0,0 using the coordinate system, and move the door to 0,0,0.
8. then move the door posts up in Z until they are high enough but still intersecting the floor hex a bit.
9. save the file as a .STL, and as a .3mm in case you need to tweak or edit it. Done!
I’ve done this for a lot of files now, and you can get really creative with it, but this is a very simple method that works with a slicer you probably already have installed.