I bought my 3 oz. Krylon Short Cuts clear gloss spray at Michaels for just $3.49. If you use it wisely, it can last you a long time!
I was using my 2012 Tokidoki calendar as my scratch paper since I honestly had no newspapers to mess up but it is up to you on what you choose to use of course! Doesn't have to look cutesy. Just note that the can comes with it's own instructions on how to use the spray but I used it with my own discretion since I was not using it to paint over anything.
Remember to spray both the front and back side of your piece. I recommend starting off spraying the back, wait a couple of minutes for it to dry, then flip it over to spray the front.
Ta-dah! You're all done! Ever seen how some girls on YouTube quicken the process of their nails drying by soaking them in super cold water? It's the same idea here.
My first experience using it, the results came out to be a little sticky. It was most likely due to me accidentally overcoating my necklace with it at the time for my Tomb Raider cosplay. But let's say you have a lot to coat on a piece you own but don't want to coat a different texture that its attached to. It is also just as simple as the above example.