I need a printer that I can keep in my car in the hot summer months, for making copies of important documents such as contracts, that I frequently have to turn in. I already have a portable scanner which can scan to an SD card, and a SD-to-USB adapter. So what I would need is probably a printer that:
Does not use InkJet technology, since ink dries up from the heat in the car. Technologies I've found that can work: Laser, Dye Sublimation, Thermal Wax Transfer, Direct Thermal, maybe some others?
Can print at least on at least 4"-wide paper (at least 5" is strongly preferred)
Can run off of a battery. Or at least, have a DC input, so I can connect an external battery to it.
[preferred] Can print off of a USB stick or a memory card, so I don't have to get another scanner. In general, might be worth mentioning, printing over which of the following it supports: PC, Mac, USB, SD, WiFi, BlueTooth, PictBridge.
Also, things that I don't care about, but might be important for others in this situation, so it might be worth mentioning if you know:
Can it print in color?
What paper / ink does it use, to help gauging the cost per page?
Maximum length of an image it can print.
Number of seconds it takes to print a single maximum-size picture.
How frequently does it jam / have other technical issues?