The Wonderland Board

When I placed Metal Boxes on water in the editor they sank, but if I put them in lava they just float on it!

Any workarounds?

None, except for putting them there with a conveyor.
This isn't new. In fact, it's so old people have started to forget about it.

If you move another metal box on ice heading for the floating metal box then the floating metal box will be moved off the lava and the other metal box will be in the lava.