Hi, bewitched, and welcome to the forums. There isn't a board editor at the time, though Mike is thinking about releasing that kind of abilty in the future. What we do have, though, is a Super DX Ball user submissions forum, including a User Created Boards thread so you can submit your ideas and designs. You can find the thread in question here.
I'd think a board editor for SDXB would make a great feature! This reminds me of F-Zero Climax where you can build your own courses and race them! (I don't live in Japan, I went to http://www.play-asia.com a year ago and bought F-Zero Climax there. Play-Asia sells Japanese version video games.)