Koro Koro no mi seen on episode 747 of one piece is a paramecia fruit that lets the user turn into a train making them a Rail Car human. theres only 2 techniques
Bakudan Ame
While rolling on the tracks with his feet turned to wheels, Aveyron pulls out a large amounts of explosives from the compartment on his back, and tosses them forward, raining explosions around his targets in front.
Hyper Special Express
He reaches into his compartment and pulls out many different parts including cannons, an engine, oil drums and a silver hammer. He then attaches this to the chassis of his cart, upgrading him to the fore mentioned state. Due to the included new engine he is faster in this state and can fire the cannons attached to him, giving him more power and speed.
My idea is also that he has a 3rd ability letting him turn into a rail cart man (so he can use the abilities)
Also you could store items as rail Cart Form. thats my idea
the ability could be called
Rail Cart man but the name is up to you guys to decide. thank you for reading my idea and taking the time to consider it (if u did) either way thanks for making such a cool mod! (sry if i had grammar mistakes)