Painting "Block" Holder

My wife has recently gotten into watercolor painting, and the paper she uses comes in a thing called a block. There are times when she would like to have the block not flat on the table, but at an angle. So necessity being the mother of invention, I made a block holder with adjustable angle. It turns out that the "adjustable" part was a bit tougher than I thought it might be.The completed projectI had some spare spruce/pine/fir from the potting bench project, so I used that. The block is 9" x 12" and I'm making this thing 12" x 14". I had remembered a book holder project that Matt Estlea did on YouTube and I thought I'd make something similar.The two frames are half-lapped together. The top one will get a horizontal member that holds the adjustable "kickstand" and the bottom frame gets a third front-to-back stile that has notches cut in it to receive the lower end of the kickstand.Front frame partially doneHalf-lap jointsThe kickstand cross-piece has to swivel to allow different…