# Aligning the faces of two models

I have two models, for simplicity let's say an Octahedron and an Icosahedron, and I'd like to move the Octahedron so that a particular one of its faces aligns with a particular face of the Icosahedron, so that I can then join them into one model.

I am fine with translating, rotating or scaling either model, I just don't want to distort them.

Once I've got them aligned, joining the faces is the easy bit. I can also do the scaling pretty easily since I just measure two edges find the correct ratio and scale one model by that value. I can do all that, but I don't know how to move them so they perfectly align. Trying to do so manually they are still misaligned after tweaking things. I would like to do this operation more than 50 times in total, and even though I will likely get better with time, it just doesn't seem like a viable method.

This question is very similar but it's constrained to simply sliding parallel faces the right distance along an axis. My faces are not parallel and need a more complex set of transforms to align them.

In short I'd like some way to take two congruent or similar faces and translate one of the models so that the two faces are incident. Is there a good way to do this?

• Do you need the faces to be scaled to one another, too, or just centered? Dec 31, 2022 at 17:17
• @RobinBetts I can measure the lengths of the edges and calculate the scaling factor myself, so in principle I don't need it, although it would save some time if I could do it all in one. Dec 31, 2022 at 17:20
• It's a paid solution so I'm not posting it as an answer, but I'd recommend the "3 Points Align" addon: blendermarket.com/products/3-points-align You just choose three points on two objects and it aligns them, with an option to scale ("Match Distances"). There's also the free MeshAlignPlus addon: github.com/egtwobits/mesh_mesh_align_plus/releases which works, but much harder to use. Jan 1, 2023 at 21:14