My advice to attach: Hot glue gun is your friend. Seems to hold on very well so far, easy to do and easy to undo.
I just designed a simple, small, generic tool holder that is designed to hold a putty knife, a small ruler, tweezers, screwdriver, small files, etc.
Looks pretty clean mounted on top of the reprap discount XXL LCD screen, seen here on this Robo3D
Protip: stuff a bit of cotton in the bottom of the putty knife holder, so it doesnt sound so violent when dropping it in.
Here's how I approach something like this.
Step One: You can use masking tape to attach this to the side of your printer, leave it there, use it for a bit. You might find after a few prints that you don't find the first place you picked to be convenient.
Step Two: Once you are sure you know where you want it you can secure it with hot glue or crazy glue. Hot glue can be undone pretty easily.