The miniatures come prepainted but as tiny bits, like a croissant, or a lamp, or a sofa. So it's not so much about painting them as it is gluing tiny magnets to them and making small installations that are repluggable.

Some of the items have tiny electrics inside, e.g. an actual tiny LED lamp.

The "scenery" (much like Warhammer battlefields) are then made from cardboard and hobby materials. You can also buy them pre-assembled, but they're much less impressive (usually one color, generic, e.g. "doll house" or "house sliced halfway"). There's a subgenre for 3D printing the scenery.

My wife uses small glass jars upside down. so the items live on the jar's lid. Looks very cute with a small LED lamp and lights off.

I think none of this is rare, but surely some items are more unusual than others.

The rarity comes from this being a hobby that not many know about.

Tiny magnets seems to be the item you run out of.

I just bought the other day a fully smol garden/green house! It also comes with tiny lamps and a battery.