Sorry for the poor image quality. I may replace them someday, but I think these are good enough to illustrate the process.
Step 1: Materials
The next thing you will need is a piece of a hard flat ruler to glue your scale and tube to it. You will also need some epoxy resin and/or a laminator to glue and waterproof the printed scale, but I recommend you use both. You'll probably need a syringe, a syringe needle and some lighter fluid to clean the tube from the ink.