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I have a curve that I've projected to a cylinder, and would like to extrude from the cylinder (see picture). Despite what it looks like, the curve in the picture is 100% closed. the shrink wrap made it look funny.

I want to extrude that curve normally to the parent 3d surface such that the curve is 'embossed' onto the cylinder. I plan to export this for use in CAD programs. normally this would be trivial to do in solid works, creo, or inventor. however, this curve has something on the scale of 800 segments, however, each CAD program is limited in the number of line segments that can be used to form an extrusion surface.

I know there used to be a knife tool that could subdivide a surface along an intersecting path, but I'm not sure how to do that exactly. the docs on the knife tool say that K or shift K will activate the knife tool, but this does not work for me, neither in Object nor in Edit mode. The docs also say that the knife can be activated from Toolbar > Tools >...., but what blender calls my "toolbar" has no option for "tools". I'm not sure what's going on, The docs are for version 2.8, but the latest is version 4.0. The version 4.0 docs have 0 mention of any knife tool, so naturally this is extremely confusing. I've tried using some modifiers to "thicken" the curve, but this doesn't seem to give the intended effect, instead duplicating the curve with an offset corresponding to the thickness of the modifier.

What's the correct workflow to extrude the curve pictured normal to the cylinder's surface?

enter image description here

edit in response to the posted answer: there is no option in the RMB menu to convert the curve to a mesh. enter image description here

edit 2: the knife-project error:

enter image description here

edit 3: the scene in question: https://drive.google.com/file/d/1LCY_wrtbBFU9OlKtxihHu4cpfi1s4lYU/view?usp=sharing

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    $\begingroup$ You could either apply the Shrinkwrap modifier of the curve, convert to mesh, extrude the mesh, or project the shape onto the cylinder with the Knife Project too, but you need to be in Edit mode, then Ctrl LMB on the shape (it needs to be a mesh object) and top bar > Mesh > Knife Project. But maybe show the object you'd like to achieve or even share your file $\endgroup$
    – moonboots
    Mar 3 at 17:29

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You could use the Knife Project tool:

RMB to convert your curve shape to mesh, place it in front of your cylinder:

enter image description here

Select the cylinder, switch to Edit mode (Tab), choose the front view, press CtrlLMB to select the shape, then Mesh > Knife Project:

enter image description here

It will leave the shape onto the surface of the cylinder:

enter image description here

Extrude the new faces:

enter image description here

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  • $\begingroup$ Thank you for your answer, but see the original post, my RMB menu has no option to convert the image curve to a mesh. Also, I need the extrusion to be normal to the surface, not unidirectional. $\endgroup$
    – tuskiomi
    Mar 3 at 18:07
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    $\begingroup$ You need to be in Object mode to convert to mesh, as for the extrusion, press Alt E > Extrude Faces Along Normals. $\endgroup$
    – moonboots
    Mar 3 at 18:17
  • $\begingroup$ Thank you for holding my hand through this. I appreciate it. I've found the options. One last thing, I'm getting an error "No other selected objects have wire or boundary edges to use for projection" when I try to knife project. I'm not sure what could be causing this, it looks to me that even using the camera as a projector, the knife utility should work. I've left a screenshot on the OP again. $\endgroup$
    – tuskiomi
    Mar 3 at 18:31
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    $\begingroup$ Have you converted your cutter object to mesh? Once done, select the cylinder only, switch to Edit mode, Ctrl left click the cutter object and Mesh > Knife Project, it should work $\endgroup$
    – moonboots
    Mar 3 at 18:38
  • $\begingroup$ oh man! thank you so much for the help! you explanation showed what I was doing wrong. The cylinder needed to be selected in orange, and the extrusion face needed to be the dark red, I had swapped the 2 around. it worked wonderfully! $\endgroup$
    – tuskiomi
    Mar 3 at 18:56

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