Jewelry mirror modular design

I'm making a standing mirror jewelry box where the mirror is framed and will be on slides that slide left to reveal ~4" deep jewelry organizer. I'd like to come up with a nice way to make the organizer a modular system where the "trays" for different type of jewelry could be re-arranged or swapped out. A "tray" would be across the internal width of the box and would be things like necklace hooks, padded ring holders, bracelet shelf, a drawer tray, etc. Well, that's the idea anyway.

So far, I've thought of a few options:

1. Make a bunch of evenly spaced "housing" notches on the insides of the long sides, then notches on the tray sides such that they could just slide in. It'd be simple but I don't like that there'd be empty housing notches where there is no tray - for example, for three slots or so below the necklace hook tray. I could create some blanks to fill those unused notches I suppose.
2. Locking French cleats. The entire back of the box would just be a bunch of French cleats; matched with the trays and dowel cleat locks. Same flaw as above with the unused cleats looking not great. Also, not a great way to hide the unused cleats.
3. Embedded metal bars and rare earth magnets. Embed rare earth magnets in both sides of the tray and metal bars evenly spaced in the internal frame sides. I suspect a little 1/2" 5lb pull strength or somesuch would be fine for this purpose. Maybe with a thin veneer over the bars on the frame to hide them.
4. Holes and dowels/shelf pins. Could drill evenly space paired holes down the sides with either dowels or shelf pins. Then cut a groove in the tray endgrain such that the trays slide down and sit on those dowels. Again, empty slots look bad but look less bad and would be easier to hide with some plugs.

Anyone have any other ideas for achieving a modular design like this?

You might not like the magnet idea. Check the jewelry with a magnet before you build. A lot of clasps and pins on costume jewelry are magnetic.

Why make empty housing notches where there is no tray? Just leave the sides plain.

I made this jewelry box for my wife and it uses magnets to hold the doors closed.
Attachment 515620Attachment 515623
It has drawers that slide in and out on wood runners.
Attachment 515621