3DPrinting
3DPrinting is a place where makers of all skill levels and walks of life can learn about and discuss 3D printing and development of 3D printed parts and devices.
The r/functionalprint community is now located at: [email protected] or [email protected]
There are CAD communities available at: [email protected] or [email protected]
Rules
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No bigotry - including racism, sexism, ableism, homophobia, transphobia, or xenophobia. Code of Conduct.
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Be respectful, especially when disagreeing. Everyone should feel welcome here.
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No porn (NSFW prints are acceptable but must be marked NSFW)
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If you see an issue please flag it
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No injury gore posts
If you need an easy way to host pictures, https://catbox.moe/ may be an option. Be ethical about what you post and donate if you are able or use this a lot. It is just an individual hosting content, not a company. The image embedding syntax for Lemmy is 
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To answer your question (and not just recommend another piece of software instead):
Making a cylinder and deleting the cap faces makes what's known as a non-manifold mesh. To my knowledge this means you can see the backfaces without travelling through any existing faces (in your case, you can see them by looking through the holes you made when you deleted the cap faces).
That cylinder has walls that are theoretically infinitely thin, so you should thicken them up before attempting to print it. You can do this with a Solidify modifier. You can also extrude and scale them if you like, it achieves the same effect.
Given a manifold mesh, your slicer will treat the inside (as in, the direction the backfaces are pointing) as solid, and you can change the density and infill pattern to whatever you like.
Make a few of these shapes, both manifold and non-manifold, and see how your slicer reacts when you tell it to slice them.