I think an option for presented boards in the board editor should be a 14 by 14 by 14 cube board for 3d chess variants. On this cube board I'm thinking the king would move one cube in any direction, and the queen would move any number of cubes in any direction. The amazon would be able to move like a queen, move like a (2,1,0), (2,1,1), or (2,2,1) leaper, and the general would be able to move like a king, move like a (2,1,0), (2,1,1), or (2,2,1) leaper. The grasshopper would hop over a hurdle, moving one cell beyond the hurdle, and could move in any direction. All the other existing pieces would have movements that could be described using only two dimensions, or in other words have (m,n,0) movement.
Some 3d pieces I think could be added to the board could be
1. The Jedi which would be a (1,1,1) rider.
2. The Sith which would combine the movement of the Bishop and Jedi or in other words move as a combination of a (1,1,1) rider and (1,1,0) rider.
3. The Kanselier which would combine the movement of the Jedi and Rook or in other words be a combination of a (1,1,1) rider and a (1,0,0) rider.
4. The Lord which would combine the movement of the Bishop and Rook or in other words be a combination of a (1,1,0) rider and a (1,0,0) rider.
5. The Falcon which would be a (2,1,1) leaper.
6. The Eagle which would be a (2,2,1) leaper.
7. The Bat which would combine the movement of the Falcon and the Eagle.
8. The Wasp which would combine the movement of the Knight and the Falcon.
9. The Unicorn which would combine the movement of the Knight and the Eagle.
10. The Pterosaur which would combine the movement of the Knight, Falcon, and Eagle.
I think on a 3d board the Bishops would be move valuable than Rooks as Bishops can move in 12 different directions while rooks can only move in 6. Also Siths would probably be much more powerful than a Bishop and Jedi as a Bishop could only reach 1/2 of the board, and an Jdi could reach 1/4 of the board, while a Sith could reach the entire board.