How do I cut a hole in shape of a different object?

Support Basics & Interface
1

So, this is a bit hard to explain, but I want to cut a perfect hole in a mesh to fit another inside it. Here’s a pic:

blender upload.png1366×699 117 KB


I want to have the top object a cistern that will hold water. When I take off the top face, I can see the lines of the other objects poking through. I can use the knife tool or loop cut and slide, but neither of those are exact. I also need to cut a hole in the bottom plane.

Did I explain this sufficiently?
Thanks in advance.

2

Boolean modifier ? http://wiki.blender.org/index.php/Doc:2.6/Manual/Modifiers/Generate/Booleans

3

Knife project ? http://wiki.blender.org/index.php/Doc:2.6/Manual/Modeling/Meshes/Editing/Subdividing/Knife_Subdivide#Knife_Project

4

If boolean is not ok for you, you can use intersection addon , see http://airplanes3d.net/scripts-253_e.xml
If it’s only for a render you can make the materials transparent, see http://www.blenderartists.org/forum/showthread.php?286334-Modeling-with-empties post #10

5

Thank you! This did it for me.

6

@JA12 Very interesting tool this Knife Projection, but how it actually works. Have tried it many different ways but without luck. Please Be so kind and show my preferably step by step this behavior. And what means cookie-cut? My dictionary does not know this term.

7

Actually you just need to select top face in edit mode, hit I to inset face and make walls, then again select top middle face and E to extrude. Esc to stop extrude and grab z down to make inside of the basin in one go.
Then again you say “perfect hole… not exact…” What is this Perfect Hole? If that is some kind of oval figure make plane out of one bezier circle and inside of another 2D bezier curve; convert to mesh resulting plane with hole you need and incorporate that in the place of the top face. By using Limited Dissolve, ngons and Inset this can be reasonably quick turn into geometry accepting subdivide or bevel.

Knife projection works with two objects selected using Shift; first one selected will be the border of the cut and the second one will be one to cut. For this you enter edit mode with selected objects, positioned how you need the cut and press button on T-panel.
http://wiki.blender.org/index.php/Doc:2.6/Manual/Modeling/Meshes/Editing/Subdividing/Knife_Subdivide

PS try “cookie cutter” - images in G…

8

Oh, silly my, have tried with K, not from T-panel.:o Thanks so much!