Help with making castle wall solid for 3D printing

Hi! I’m new to 3D printing and Blender.

I’ve been trying to make a simple castle to 3D print.
To make the towers, I create two cylinders with different radii, and do a boolean difference.

Then I make a cube, size it to a wall, and move it so the tower and wall are overlapping. Then I do boolean intersect. Unfortunately, when I try to print this there is a vacant area where the two overlap - even though I’ve printed solid objects using the intersect before.

The picture I attached shows where the material does not print.

What should I do, can I fix it, and how do I prevent it happening again?

CastleWall2.blend (551 KB)

To clarify, in your image the round shape is the tower and the rectangular shape is the wall, correct? Is the problem that the tower is hollow? Forgive me if i have trouble understanding your question.

The round shape is supposed to be the tower - I’ve hollowed it out so I could use it as a pen holder. The rectangular shape is supposed to be the wall. You can see the paper underneath the small hole - that isn’t supposed to be there.

Below is another picture where the overlaps are more easily visible:

So is what is the most efficient way to do something like that so it can print? Is blender not optimal for this kind of work?

Could be that Sketchup is more ‘optimal’ for this shape however if you know the tools blender provides there are no problems to come up with any shape you fancy.
willit3dprint said “Yes, it will” and process to build this took not so long. No boolean abused.
Then, there is an addon BoolTool from Vitor Balbio; using this you could boolean and adjust all non destructively, then apply all boolean operations, get the resulting mesh:

“Most efficient” depends on what you are efficient with. More tools/software you know more efficient you are.

I tried sketch up but wasn’t a huge fan. I’m trying to learn the tools but Blender has a lot of information to sort through and a steep learning curve. Where would I find the newbie friendly videos/tutorials to help me fix the problems I’m running into?

Doing stuff on your own on things you are interested in creating in 3d and getting in there (or on Google) for the problems you have might be better than watching a cycle of video tutorials on modeling this or that. If modeling is what you need for 3d printing you can explore just this part of blender leaving out 90 percent of other things Blender can do. course covers a lot, might be slightly ‘not entertaining enough’ however is well done and categorized.
Modeling topics here on forum - worth to browse around and see what others struggle with.
Terminology might be a big obstacle - you know what you would like to do but do not have a slightest idea what to look for. There is no other way as to just read random. Sooner or later you’ll find the answer or get familiar with therm.

Explore tools and be back with questions like “how would i…on a model you see here” ;).
Have fun!