I'm a newbie with editing stuff in SimPE, so I need some visual guidance.

Making items shiftable - https://modthesims.info/t/316879
(Also see the post I made at the bottom, it's a quicker trick that saves you time finding all the lines in the boxes).

This works on most one-tile deco items, wallhangins, and some usable items.

The trick to the items not turning black is to move the mesh itself to the floor, and only shift it up. It's the downshifting that turns the item black. You need a mesh program to move the mesh down, and it "only" works for deco items - it's not adviceable for usable or animated items unless you know how to mod them to work properly as shiftable items.

If you keep the original position of the mesh of a usable item, you can make it shiftable and it will keep the animations, but the animations will jump into position, and depending on item some may not work.

@simmer22: thanks for the link. So if I understood correctly, do I need to have experience with Milkshape to eliminate the blackness when shifting down?

A bit. It's a very simple edit in Milkshape, so all you have to do is to select all the groups in the "group" tab (selected groups show red in the viewports), then switch to the "Model" tab, select "move", deselect X and Z (this makes sure you don't move the items in other directions than up or down), and move the items down toward the grid line but not below it (as far down as you think is useful - most of the time you probably wouldn't put a picture all the way down on the floor) and then export as OBJ.

Make sure to keep the original names, and to have the "advanced mode" switched on in the SimPE preferences, so you can replace the mesh groups, otherwise I think SimPE imports the mesh as extra items instead of replacing them.

Long group names are sometimes shortened down in Milkshape, so make sure the names are OK after importing. You can find the proper group names in the SHPE.

Thank you for the instructions!