This Large Mushroom Floating Shelf has a replaceable bracket (My Free BrickBrack System) so you can easily add it to your wall, standard pegboard or skadis board.

The brackets don't need support if they are laid flat side down on your print bed. You should print them with >50% infill.

For the shelf I recommend tree support touching buildplate at 60%. I recommend a brim as well.

I find it easiest to pry the supports out of the bracket cavity with something like the tool that comes with the printers for scraping buildplates or a painters multitool.