LadyEdain

I made some per your suggestion, and they do attach at the bottom of the previous row, like they should, but they still don't look right because they don't have a shingle overhang like the bottom pieces do. Or left and right end pieces to match the ones for the regular roof pieces. I think bottom eaves (with edge pieces) are just missing.

Not sure if this is true for every roof type, but these are roof bottoms (eaves) in slate. They are clearly just the bottom half of a normal slanted block, but they need to be in the upper half of the block entity in order to join up with the row above and be a proper eave. If I'm missing some step to make these line up correctly, someone please tell me, because I can't figure it out. It looks like a design error to me. Also, there are no outer corner eaves, so for my tower with a hipped roof, I had to use full-size blocks as an overhang, because there were no outer corner eaves to match the regular ones (not that the regular ones line up anyway).

Well, QP's Chisel Tools tutorial answered my question. @Vintarian Do what was mentioned before about orienting the block you want to add. Then, to add it to another chiseled block, you have to combine the two in the crafting grid (the main block above the one you want to add to it). Place the main block where you want it, then use the F key to add material, as usual; the added block will now be there. I hope that allows you to do your interlinking. I was just wishing for a chain guardrail myself, but I think that's more complicated than I want to try; I'll have to stick to wooden handrails.

I'm not sure if I'm missing a step or if the game has been updated so this no longer works. But I put my log the direction I wanted it to go, clicked on it to make it a "chiseled" block, picked it up (in my inventory, it's going the way I need it to go), then I attempted to add it to my already-chiseled block, but it just threw it out on the ground; it would not accept it as an additional block. Am I missing something here?