I'm asked all the time about painting tiny details on earrings and the like. To be honest, I'm blind as a bat, my eyes have no aged well and it's a real bugger working with tiny pieces. 
I realized a few months back that I had to do something lol So I headed to Amazon and grabbed myself a handy dandy LED magnifying head lamp!
OMG you guys! If you don't use one of these, you either have phenomenal eye sight or you just haven't found this amazing contraption yet! Seriously. If you struggle with painting small parts, GET THESE NOW! Your eyes will thank you.
The pair I have is rechargeable too, so YAY for not having to buy batteries for the LED light.
You can grab yourself a pair on Amazon for less than $20.00, but even if they were $50.00, they'd be worth every, stinking, penny!!
