How do I Extrude A Ring of Cones?

I am trying to build a columnar cactus with a ring of small indentations where the spines would be. These are each modelled as inverted pyramids or 'cones'

You can see a ring of cones on the left cactus, this has been duplicated and the ring selected. When I extrude I lose the vertex which connects the four points to make the inverted cones.

If I extrude one of the small pyramids on its own it keeps the vertex.

But if I continue, it stops extruding the vertex.

Can someone kindly explain to me how I can extrude and keep the original ring of inverted 'cones' intact? Or is there another method to achieve this?

Thank you.

• Well, if you want to do it like that, then only possible way is to do it this way and clean vertices that are needed to be removed afterwards... I would personaly do it differently.. First make those rings without those holes inside, make whole cactus and then select vertices where holes are supposed to be, use bevel -> choose vertices, make those squares, extrude inwards and connect 4 extruded vertices in one (in the center of those 4) I think it would be easier and less destructive Aug 31, 2021 at 9:25

Then select all corners and press Ctrl + Shift + B

Switch to face select mode, then press Alt + E - Extrude Faces Along Normals

Chose transform orientation - individual origins

Then scale all down to 0 press S then 0

Finally, press M -> by distance

• Perfect! Thank you. Aug 31, 2021 at 9:37

Generate a "perfect" cactus.

The concept here is to make just the one section of the cactus and repeat it.

Add a circle, keep an integer fraction of it, by deleting other verts.

Example one eights of a circle, arrayed into a full circle with object offset using empty. Empty is rotated (360 / 8 = ) 45 degrees. Array count is 8.

Hindsight TIP. Rotate such that the center of arc matches Y or X axis making it easy to edit in front or right view respectively. eg clockwise 22.5 degrees to align to X

Taking care to keep our end vertices on same vector from origin and at same length, edit the profile suit.

lol, total mouse misfunction hassles, going to look like a plastic wall plug, but its the concept that counts

While editing profile one option To ensure these verts keep there place is to hide the end verts (select them H unhide with AltH)

In gif above have scaled two end verts about the scene cursor pivot point, at circle center.

Make an unlinked object copy to keep that profile. Later will add an array modifier to grow in Z. Use the profile to make end caps.

Then A Select all, and extrude in Z EZ

Another array modifier is used to copy this section in Z.

So, here is my plastic wall plug thingy to hang pics like this on walls. Anyhoo, the concept is making the divot once. Edit mode all faces selected.

Can later apply modifiers and edit, or add modifiers to randomize

Here is above bent out of shape with a 4x4x4 lattice.

• batFinger thank you for a totally brilliant answer. i love this workflow, I need to dig in and learn something here, this makes sense with a lot of other applications, entertaining too as far as these things go. Thank you! Sep 1, 2021 at 21:10