[It's not something impossible, not in Bulma's mind. On paper and theory creating a machine that allowed moving between dimensions as well as time and space shouldn't be out of her reach. Not when she has two thirds of that covered already. The problem, though, would be remembering to work on that once she returns and knowing where exactly to go once the machine would be completed.]

Maybe you should gather data about your friends' worlds and universes then. If there's a way out of here that allows us to keep our memories I could try to build a machine that would allow you that.

If I started working on it on my time, maybe it would be done by the time you're fifteen.

[It certainly would give her a lot of time to do it, which is appreciated as she technically hasn't built a time machine yet.]