Building a ir laser pointer

if i buy an ir doide off ebay can i make it into a pointer?

Probably not. Its not impossible, but there's a lot more to it. To be brutally honest, if you're asking this question, its 99.9% you don't yet have the skillset to even consider taking on the task. With a good amount of research and a bit of money to blow on experimentation and prototyping though, its certainly a possibility.