"Still think apple trees need to be spaced 8-12 feet apart? ...use small trees spaced close together... Apples can be trained 18" apart on a fence or trellis like a grape vine, planted 2' apart in a hedgerow, or planted 4-to-a-hole, 18" apart. These apple trees can be kept any size by utilizing summer pruning, no matter what rootstock they have.
Growing Raspberries in mounds I like this idea because it keeps thorny raspberry bushes in one controlled place rather than seeing them spread all over the place. I love raspberries but the plants are not that pretty.