This is a simple yet effective approach for height-adjustable bases for flying minis in any table-top RPG.

I used these extendable Rods: https://www.ebay.de/itm/5x-Teleskop-Magnetheber-Magnetstab-Chrom-ausziehbar-Magnetgreifer-560mm-silber/392502930634?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

but if you are not from germany you can search for any telescopic / extendable magnetic rod for picking up screws or dropped keys from unreachable places.

The model here is designed for rods with 7mm diameter. If you get ones which are thicker you have to modify the model a bit.

If you really go all the way up and got a model on the top you maybe have to put some heavy steel washers on the base to stabilze it a bit.

I just glued a small strip of metal on the bottom of my mini so it holds super strong on the magnet.