Camera Lucida: Easy solution to use with the app

I took a banana box and cut a door through the long side. On the top is an opening for the iPad and you can use a ruler to lay across the opening if you have to balance a smaller iPad or iPhone.

The box is big so you have good room for your paper A4 or A3. It is also easy to cast a light through the top or through openings at the edges or short sites.

Good luck!

A wide opening gives you a good room for sketching
My iPad is secure at the top but I slided a ruler under it to prevent it from falling down.