I forgot about those magnetic bowls. Great idea!
You could cut a photo or piece of paper to the same size as the glass, then use a stiff piece of wire (maybe a piece of a coat hanger) cut just a little longer than the diameter of the lid. Put the picture in the lid, bend the wire just enough to get it to fit inside, and the tension should hold the picture in place. You may need two wires in an x shape to keep the paper against the glass all the way around.
Edit: I just realized that the wires might keep the lid from closing all the way if the rim of the bowl goes all the way into the lid. There's always clear tape.
I was trying to think of a way to do it with no glue or tape visible through the glass, but see the edit to my post. It would work if the lid fit inside the bowl instead of the bowl inside the lid, but I'm not sure how those bowls are.
Ya I'm thinking about cutting out little tabs outside of the circular paper that can be taped to the outer edge of the lid on the inside. Then a small piece of tape in the middle to prevent sagging
It´s a very good... I would try one metal frames, like those girls use to put pictures in their rooms, of course smaller and more appropriate, something like this:
as the finest support. In addition the board staff of the Portuguese language uses print when you do not have boxes where cut marks soaps and print photo paper, see here.
Just throwing this out after a few moments of thought:
scan label.
print to photo paper.
Take lid and trace circle around lid over photo.
cut out photo and press into lid.
i think it might work because the Grundtal lid is slightly domed so because the photo will be slightly larger than the interior dimension of the lid (because tracing was from outside diameter) it would naturally bulge out.you may have to make a small cut in the photo from the edge towards the center to make it fit better and allow the photo to curve more (think of rolling a cone shape from a rectangular piece of paper.)
Hmm, I may have to go back to Ikea and buy a set to try this out...
If you have access to a laminating machine you could try that ie, print your desired label/image and laminate the sheet (say an A4 size sheet, you could get 2 labels on that most likely) then cut to size - the added stiffness of the laminate might help secure it inside the lid too.
I know it seems like a lot of bother, but if the soap is going to last a while, it's not so bad - it's not like you'll be doing it every other day
Have you tried leaving the lid off for an hour or so after use to let the soap dry - or does this still affect the label?