In a previous post, I mentioned that multi-carts could be used to achieve minecart jumps. Since I am currently testing my own build of minecart jumps, I will take this time to refer readers to the crafter from whom I first learned about minecart jumps, the youtuber Pwegoable. Pwegoable named his minecart jumping structure a "minecart launcher", and as far as I know he is the only person to have ever discovered this glitch. The below video is his tutorial.
I will have a post on minecart jumps after I'm done testing my own builds.