Woodworking

Here's the old-fashioned version of that: Thomas Jefferson's Bookcase. Having built a book case inspired by this of this out of oak, I've noticed no deflection. (It's structurally different, center-keyed box joints instead of dovetails, thick plywood back, various clear finishes.)

However, I can tell you that there are a few functional problems. One is that the shelves do slide against each other. The little nubbins would help, however, you're cutting the fibers of the wood or into plys. That could increase deflection. I bought some handwrought nails and may end up using them, but I like the modular nature. Another is that these shelves are not light. I had hoped to make them easy to move, but they are not light. Finally, there's no cover, so books fall out as they're getting moved. Barrister bookshelves solve these problems.

I don't like this system for two reasons.

The first being that bookshelves should have a restraint system that attaches to the walls. You could probably improvise something, but the video lacks that element.

The second is that the alternating brick pattern is weak for an open faced box. That puts a significant portion of the weight of higher courses on the middle of the span of lower courses. You can see some of the lower levels bowing signicantly. Since the back is rigid, but the front can flex, that will increase the tendency to tilt into the room and makes the tipping hazard worse. Add in an old floor that is concave and you have a significant hazard.

I like the concept, but this needs some changes before it is safe.

Edit: I'll suggest potential improvements rather than just naysaying. You could make two different width boxes. A full width and something like .8 width. You would stack the boxes alternating full width with partial width. The full width box would need 4 alignment pins and 4 slots. The boxes would stack in line vertically, but due to the alternating widths would still lock adjacent columns together. The important thing is that the vertical walls would be close together rather than landing in the middle of the spans.

Then I would add a cap board that can be bolted into the top boxes and would be used to attach a L bracket to a wall stud. Yes, this decreases portability, but not crushing children is more important than convenience.

Seems to me like board width would be the main concern. Hard (for me) to get solid boards any more than 30cm/12" wide, and a shelf stack that shallow will get kind of unstable when stacked more than a few units high. Strength wise, it ought to be fine.

I think I'd still use plywood for the back/bottoms, assuming you'll fit them in a dado, which will hide any splintering at the edges.

I think the pine hobby panels will be fine structurally. I think you mean the ones that are a bunch of smaller pieces glued together. In using these I have found not all the glue joints are great, though.

But, I suspect its the glue in the plywood that might damage the saw. Glued up hobby panels will likely act the same.

Might want to pick up a cheap crosscut saw / general carpentry saw for utility cutting and save the nice pull saw four detail work.

I would say it would be fine, the only problem would be warping as the pine will be quite thin (plywood is more resistant to this).

But if you don't care about everything being perfectly straight I think pine would be plenty strong enouph and wouldn't warp noticeably much either (just pick straight boards from the store). So yea I think it would be fine.

P.s. (if you join multiple boards together its usually less likely to warp but I don't think this is necessary for your usecase)

It's doable but....

Figure out how much the heaviest load is and use a span/shelf calculator to make sure it'll hold. If you offset each level, like in the video, I doubt there is any concern.

Pine doesn't machine as well as good plywood. It'll take significant work to make each hole for those pegs in such a way that there isn't tear out... And if you don't seal.it with something penetrating, will probably splinter quickly with use.

At 30cm wide, are you jointing boards?

Whatever you do, come back and post pics!