One of the more popular techniques that has grown in recent years is the use of rare earth element magnets, to allow model parts to be attached and intechanged or removed for storage etc.
There are lots and lots of you tube videos on the subject. So I won't be going into the technical details. However someone asked me if I new a UK supplier.
I didn't at the time. However I do now
Found the link in a you tube video.
The other source appears to be ebay for many.
Size wise, I am still looking into this. Partly for my starship troopers miniatures. But also partly as some scenery pieces that I fancy making to be able to seperate for storage.
So any way a brief post on the topic.