There’s a whole thread on that topic that lasted almost 10 weeks where one of our members @ExtremeElementz struck gold with a profile he put up on MakerWorld. I took his work and on that basis alone, was able to tweak and re-tweak.
It was so long ago that I had to read through the thread myself to remember some of the things I had to do to get to that point. Check out the thread and you can how I did it. Just to be clear though(no pun intended), that cube took nearly 10 hours to print. The secret is in very high temps, slow travel and generous use of aligned rectilinear infill. Also, one must eliminate all walls and have the filament just zig-zag back and forth. The last step before post processing is of course ironing. What you will have is as close to an optically clear cube as one can get so far. I haven’t found any more than the one filament that achieved that which is in that thread. However, you will still struggle with the fact that the top layer is not perfectly flat. For that we go to sanding and a layer of clear polyurethane which gives it that final wet look. The clear interior does the rest.
I just finished a rough version of magnetic switch that I am experimenting with. In this example, I have a lot further to go. But my goal in this case wasn’t to print something optically clear but something “close enough” to allow me to verify the positions of the magnets as I turned the switch.
This photo is still a very rough version but it shows you other applications it can be used for.
I also have a rose cube that I’m experimenting with. I may post it here if there is enough interest.