Ask Engadget: best mobile printer?

We know you've got questions, and if you're brave enough to ask the world for answers, then here's the outlet to do so. This week's Ask Engadget inquiry is from Ryan, who needs a device that'll save him time out on the job. If you're looking to ask one of your own, drop us a line at ask [at] engadget [dawt] com. "Hi. I'm an electrician that travels around in a van all day. Right now, I can either write receipts by hand or email to my customers after the fact. Is there any printer that I can use ...