Book Stand (suitable for large and heavy books)

A bookstand, which is suitable for heavy books (cookbooks, for example). The tilt angle can be adjusted in 30° increments. Both sides should fit together tightly. I used a hammer to connect them with (careful) strokes.

Also needed: two screws M4x10, one screw M4x16 and three nuts M4 (in DIN 933).

The shelf has twice the size of my heating bed (its usable area is 200x170mm).

UPDATE 22.06.2018: Added two parts to keep a book open. It is simply clamped in the existing bookstand (and requires another M4x10 screw, a self-locking nut, and a washer). I also added an (alternative) leg - for more stability with non-centered books. 

UPDATE 02.09.2018: Added version 2a with a modified SeitenHalter.

The version in the photos is printed in PLA+, but it's also stable enough with PLA. In total, 88 grams of filament are needed (@my configuration).