1.Confession dial: uses the same dimensional engineering as the tardis just on a smaller scale and could be used as a jail with the vale

2.small tardis: could be a easier way to shrink the tardis instead of using the block data command

3.sidrat: a non bigger on the inside tardis it could be like a elevator with the sb-129 panel

4.medium sized tardis: same as the small tardis

5.sontaran teleport: could be used as a cosmetic exterior 

Nice ideas