Slant Board Build with Scrap Wood

In the Starretts' and Glen Cordoza's Deskbound they recommend having a slant board under your standing desk, to further add variation to your standing habits (stand on it to stretch the calves, use it as a foot rail, etc). Since I've used a standing desk at work close to ten years, I figure it was about time to get myself a slant board, but the nice US wooden ones cost a fortune in shipping and customs and the locally available ones were just too plastic, so I checked out the photos of a nice one online and set out to build something similar myself. Here's the result:

As can be seen below, the top board is not one but two joinced pieces of some upscale panel that the contractors left after our kitchen renovation the other year. After I had sawed the uneven side straight, it was 75 cm long, so after cutting it in half and joining the to pieces together (and fixating them with a couple of screws), the top board is almost exactly 37.5 x 37.5 cm (just under 15 x 15 inces). Most commercial wooden ones are around 13 x 16 inches, so close enough.

For the supporting part, I used 120 x 28 mm Sibirian Larch we had left over since we rebuilt our terrace the other year. Figuring that if a right triangle with equally long legs have the other two angles at 45 degress, we should end up at 15 degrees if we make one of the legs three times as long as the other. Since the boards are 120 mm wide, we should thus take a 360 mm long piece and cut it diagonally. That worked out very well - especially since that diagonal according to Pythagoras' theorem would be just under 380 mm and thus matches the length of the top board very well.

EDIT (2021-08-09): OK, the simple heurestic is of course flawed. Actually calculating the trigonomics shows that with the opposite leg 120 mm and the adjacent 360 mm, we get the true angle with tan-1(1/3) which gives ~18.43 degrees. Close to 15 but not quite 15. The same way, the last "third" won't be at 30 degrees but at tan-1(2/3) or ~33.69. Look like I would have needed a 448 mm long diagonally cut board to really get a 15 degrees angle (tan-1(120/448) ~ 14.995 degrees).

Finally, given that the top bord already had a number of convenient recesses, I gave up on making the slant board adjustable at exact degrees of angle and just cut a suitable piece of board with slanted end, fastened it with hinges - slightly off centre to prevent it from falling down between the two bottom boards - and verified that I could use it to have the top board fixated at a number of different angles with at least one with the top edge half-way up my shin to work perfect as a foot rail.

Working beautifully!

As I intend to use this first one mostly at home without shoes, I'm not sure whether any anti-slip tape really is needed, but it sure looks nice with it added. Now I just hope I will be able to muster up enough scrap wood to build a second one to have at work.