Here is a collection of Fan designs i have from theories going on in the show Kamen rider Build its mainly going to be along the two lines of
TranSteam and ProtoBuild
KR Pandora + Pandora Panel Driver - fan design based on the idea of turning a plot relevant item (the pandora panel which is part of pandora box) into a functional driver with a matching form.
SpringerRabbit - based of using an adapter similar to the seconed rider that used a Dragon themed one called ClawsDragon with matching form
with the appearance of 2 villians who use a gun like device to transform unlike the main character it leads to alot of Possibilities for forms that e will probably never see similar to this other piece i did for the previous series https://www.artstation.com/artwork/2aL0y
Mirroring Transteam of a secondary style exploring organic full bottle forms Protobuild is a prototype form of the main character with a prototype driver that only uses non-organic full bottles