http://www.amazon.com/Huion-Diagonal-Artcraft-Tracing-L4S/dp/B00J3NRAV2. Basically you put your masking Material over the clear part and turn the light
on and whammo, it shows up. You can make your own :https://www.google.com/search?q=diy+tracing+light+box&oq=diy+tracin&aqs=chrome.1.69i57j0l3.7624j0j4&client=ms-android-verizon&sourceid=chrome-mobile&espv=1&ie=UTF-8