Set your desired blocks you want to be randomly placed when you're on a train or a contraption. You can either set a filter with equal chance of being placed, set a filter where you can set each blocks percentage chance of being placed, or set a sequence filter so the placed blocks will follow a set sequence pattern set by you.
This works on both Trains and Cart Contraptions, Deployer and Rollers.
See Asgar's original version of this mod (1.21+) https://www.curseforge.com/minecraft/mc-mods/create-randomize-filters
