Hi all. I needed splines for a thing i'm working on, but decided to go a different route, so I created Squigs. ("squiggles").. They're sort of a line-and-round-rect version of splines. You give it a start point and an end point (and control point, maybe) and it draws you a line that connects and looks nice.
You can find it here: https://github.com/BleuLlama/Squigs
MIT License, feel free to use it in whatever!
It boils down to one small .lua file that does the thing, although there's also a sample app that lets you try them all out.