I use an old, OLD, copy of Photoshop. Some members here use GIMP which is free to download. I haven't taken the time to get used to GIMP due to the fact that you currently cannot print directly from it. One must same the work, then open it in another application (such as Paint, Photoshop, or PhotoViewer).
I look forward to seeing your build. BTW What scale are you building in?
I also print directly with Gimp. Make sure that you have merged all layers before printing; otherwise only the active layer is printed. To keep the layer structure of the original file intact you may choose to do this: Edit > Copy visible > Edit > Paste as new image and then print the new image. Also make sure that printing resolution is correct.I've been been using GIMP exclusively, and printing directly from it, for quite a lot longer than a year.