# Make holes in complex curved surface for subdiv

I need to make a chair with many holes in it.

I made base carcass with subdiv

But how do i make holes? Problem is if i add more topology to make this holes there too much topology and i need to make every little bit of this curve by hands (with prety much impossible or too much work). But if i try to add holes after subdiv there too much mesh and problems with shading. Is there a way too make it without spending 40+ hours moving every verticle to its place?

• did u try boolean modifier? Apr 4, 2023 at 4:21
• i ask how make it easier, not harder :) Apr 4, 2023 at 4:59
• then u should improve your question and write what you did try and what you don't want....how should we know? Apr 4, 2023 at 5:47
• I didnt know that i need to explain that subdiv and boolean dont work well together. I thought its common knowledge. My bad. Also its almost impossible to make this shape using boolean... Apr 4, 2023 at 6:24

Supposing you have already created the form of your seat as a single skin:

Then one way to retopologize a portion of it, so you can simply remove faces to create the slots, would be, with a helping hand from Geometry Nodes, to extract 2 matched edges from your form:

The top edge is duplicated from part of the boundary, the bottom edge is the result of a horizontal Bisect operation, with both the 'Inner' and 'Outer' cleared. They're converted to curves, which can be resampled to matching counts with a tiny GN modifier:

So, as on the right above, they can be Converted back to Mesh, linked with Bridge Edge Loops, and have a couple of even cross-loops cut in.

The cross-loops can be bevelled with 2 segments, and a selection made as shown above, with the help of CtrlShiftNumpad +. If you delete those faces, the resulting topology survives Solidify, Bevel , and Subdiv modifiers, when eventually assigned.

There various routes to deriving the seat-base from this geometry (Grid-Fill and projected Shrinkwrap to your original form?) .. I guess that's another question.

• Amazing. This exactly what i asked for. Thank you very much. But what about bottom? Connect it by hands? Apr 5, 2023 at 10:23
• I won't deny its fiddly, I've gone far enough with it for proof-of-concept, before posting. My method was: (Still in single-skin,) 1. F close the bottom edge to cyclic, subdivide the closing edge to roughly the same density, ensuring an even count in the whole loop, and Grid Fill. Then shrink-wrap the seat in Z to the original form. (The shrink-wrap can be aimed at a vertex-group, and adjustments weight-painted in) Apr 5, 2023 at 10:42