1) Whenever anyone mentions something to you - your reply is: 'I can make that !'

2) your house/workshop is over run with little plastic models, doodads and fiddle widgets.

3) Your friends see you coming and run before you give them another useless piece of plastic

4) Your christmas gift list consists entirely of weird filament types.

5) You only intend giving gifts this year that you've actually 'made' yourself (for 'made' read mostly downloaded from thingiverse)

6) Even your anorack has 3d printed plastic toggles.

7) You spend your life hoping household items will break, so you can make your own.

8) You sincerely believe that you will invent and print something that will make your fortune.

9) You believe that self-replicating printers (rep-rap) is a real concept because you can make a few plastic parts. While ignoring the fact that you have to buy all the metal, motors, electronics and actual printheads.

10) One day you hope to be able to print your own replacement body parts and become a truly self made man.