The idea behind these is to effectively double your book storage on tall shelves. The design is mostly parametric. Width and height are adjustable to best fit the kind of books you want to store. These shelves feature self centering connectors, ribs on the inside to prevent the bottom edge of your book from riding up on the internal fillets, and a backstop to prevent your books from sliding all the way through. All files are printable on a mk4/core one build-plate. Would I stack 3 like in the pictures? Absolutely not. It'd be stable on a bookshelf but it has more wobble than I'd like. 

Files Included

I've included two sizes:

• Manga - Standard manga is 7.5"x5" (or 190.5mm x 127mm). The internal height and depth is 195mm x130mm.

• Mass Market Paperback - Sizes are 6.87" x 4.25" (or 175mm x 108mm). The internal height and depth is 180mm x 110mm. (I haven't tested this size since most of my books are hardcover)

• The step files as well as the onshape link are included so these values can be adjusted how you see fit.

• The inner width of the standard shelf is 185.2mm from rib to rib. This can be adjusted. The outer width is 194mm. The limiting factor is going to be the size of your printer. 

• The onshape link can be found here.

For each size there are three models to choose from:

• Standard - Has connections on the top and bottom.

• Top Shelf Cut - Has connections only on the bottom and has been bisected at the midpoint.

• Top Shelf Smooth - Is identical in every way to Standard except it does not retain the top connections. This makes it 2.8mm shorter and allows stacking of other items on top.

Print Settings

• Thick layers are better

• Use a brim unless you know that your printer doesn't have a warping issue

• I used PETG because that's what I have on hand. This will easily work with PLA or almost any other material. Use whatever you want except for TPU. I don't think that would turn out great.

Design

The models provided are the second iteration of this design. The first had some issues I needed to resolve (screenshot below).

Stability. This was originally designed to be just a double-decker model. Unfortunately I didn't stiffen it enough to ensure that it would work that way. The top shelf bows down slightly and there's a lot of side to side flex on the legs when the top is fully loaded. This was partly due to how thin I made the walls as well as a lack of stiffening on the sides. Another insidious issue was warping. The points at the very top were very prone to warping with PETG due to how thin they are. This happened even in a heated chamber and with a brim. All of these issues were either completely resolved or significantly mitigated in the second iteration. 

By going to a simpler design I was able to achieve the rigidity I wanted while also having scalability. The warping issue was still present, but due to the increased contact area, a brim resolved the issue as did swapping to a textured build plate rather than a satin one (I probably just need to do a better job cleaning it).

Future Updates

I'm considering adding slots for magnets on the side in order to better connect the shelves. Of course it'll thicken everything and at best it'll just be for alignment. I could also place alignment notches on the sides, female on one and male on the other. The downside with that is I'd have to provide two additional models without a F or M notch. And of course this would require a lot more planning on the user. I could make them all have F notches and just include a pin of some kind. Magnets or small pins are probably the easier option. If I do either of those then they'll probably go on the rear inside a thickened backplate (the yellow highlighted area on the above picture except the entire rear not just that section).