Here you have one super custom tread desk. I made it this afternoon with a piece of 1"x12" pine board.
I tried reading while walking 1mph on my treadmill yesterday, and it was actually quite nice. I held my book, which was ok, but if I have a newspaper, a laptop, a letter to write, then I know I'll want to have a flat surface in front of me. Also, I tend to move forward on the treadmill until my toes brush the housing in front, which is ridiculous because there is a mile of belt behind me-- I won't fall off the back! This table will keep my body away from running up the front of the treadmill.
I wanted the board to not rest on top of the hand controls (fast/slow, up/down), so I cut holes out with my jigsaw. I cut ovals from painters tape out of the shapes I needed and laid them sticky side up on top of the controls. Then I carefully set the board down in place and then picked it up again. The tape stuck to the spots I needed to cut out.
It was sort of handy; like almost all 1"x12" pine boards, it was cupped a little bit. The way the arms of the treadmill are, that worked out perfectly for the setting of the board, with the cupping flaring up.
I wanted ends on the board, though I didn't really need them. But because of the curve, I couldn't use a solid piece of 1"x2". It wouldn't have touched evenly across the end. So I cut 3" pieces and screwed them on, after pre-drilling.
Life is an adventure, and face it, food is a big part of life. Very good food, very bad food, and even mundane, boring food has something interesting embedded in it that can be pried out with a good opener.