I'm pretty sure that's not the type of capsule X was actually created in, but why would I try to sprite a brand-new capsule for him when I can just steal Dr. Light's holo-capsule? Well, steal it and then enlarge it 300%, reduce the transparency of that central part to 50% to make it look glassy, and then stick the half-finished X sprite inside.
That half-finished X sprite, which is partially blocked by a text box and can seen better in the comics that follow, was a sprite I made by taking a regular X sprite and messing with it. I deleted some parts, like his arms, recoloring other parts, like his head, and just generally played around with it until I had something I was happy with.
I was going for a sprite that would look like something Dr. Light was working on in his spare time. I imagine first he started working on the head, then realized he should probably work on the programming before he finished the head, but got slightly side-tracked on the core skeleton, thought up something really neat to do with the feet, like giving them the ability to dash, then found he had finished the feet before remembering he was supposed to be working on the programming in the first place, and ended up with the half-finished robot seen above.
At least, that's how I would probably end up working on it. I mean, look at all the half-finished projects I have just dealing with this website.