# How do I use the geometry of one object to make a corresponding socket in another object?

Referring to the attached picture, I want to use the peg (A) to make a socket in the face of the other object (B). This is for 3D printing, so I don't want to simply make a hole; it has to be a fully manifold socket, essentially an inverted cylinder, that peg A would fit into. I'm not even sure where to start. How can I do this in Blender?

• You need to use a boolean modifier. Move A over B until you get the desired position, then select B and use a boolean modifier with A as a target object (the default setting is difference, just what you need) Commented Sep 26, 2022 at 5:53

From the POV of an ordinary polygonal modeller, looking ahead a bit before starting the model, you might anticipate having to match vertex-counts. They are easier to fix on the cylindrical (male) side than the bevelled (female) side. So you would model the bevelled side first, and use whatever vertex-count it throws up:

• With Viewport Overlay > Statistics checked, you can see the front face has 16 vertices.
• Model the cylindrical side based on a 16-sided cylinder
• Select its peg in Edit Mode, ShiftD duplicate it, and P separate the selection to a new object
• Back in object mode, CtrlJ join the duplicate and the female side to one object.
• Delete its front face, and with snap set to 'Vertex' and 'Active' snap the peg-section along the common axis to the open perimeter
• AltN > Flip the faces of the peg-section, so everything is the right way out.

• Because the vertex-counts match, you can CtrlE > Bridge Edge Loops the corresponding perimeters, with 0 Smoothness, and a couple of cuts.

And you're done, if you want the geometry of the peg and hole identical, with good topology.

For printing, you may want to scale either socket or peg in cross-section only, and move one or both ends in depth, for tolerance.

• Very cool. Thanks for your help! Commented Sep 27, 2022 at 14:34

Creating a female mate (square cube) using a male object (a bolt with threads):

Here's 2 ways using geometry nodes. Create a gap fit (0.2 mm works for me). You can use Extude or Scale (I prefer option 0 the extrude faces)