For permanent mounds (or long lasting) bottomless boxes can be constructed. There is a site I used to manage that had semi-dwarf apples in such boxes constructed out of pressure treated wood. They were 4’X4’X4’ I think.
I manage another successful orchard that uses artificial but attractive landscape stones to created wider not as tall mounds- more like 2’ over blue clay you could make pots out of. The soil is so bad that they are useful at reducing tree vigor in probably even enhancing brix levels in spite of continuous access to water. They must be about 6’ diameter circles. I filled them with a mixture of sand and compost but probably high quality, sandy top-soil would work as well. I also blended some of the clay into the first half of the new soil profile.