Don't you love it when science and fantasy meet? Learn how to get your own scale model of a favorite princess's tower (provided you have access to a 3D printer)
Step 1: Model the Tower.
This tower was modeled in Blender, which is a free open source modeling software, great for things that have a more organic feel to them. There are many great tutorials on Youtube for using the Blender software. That is what I used to teach myself how to model in Blender. Using reference images are invaluable in modeling this kind of thing. (If you're not interested in this particularly tedious step but would like to print my tower anyway, I've attached the STL files to the last step in this instructable.)
Step 2: Ensure Your Model Is Manifold
You need to make sure your model is what is called 'manifold' otherwise the slicer that generates the code for the printer will have a hard time doing its job.
Manifold means that the model is "water tight" or there are no gaps in the model. the best helper I've found to do this in blender is Ctrl+Alt+Shift+M. That will automatically select all things that are making your model not manifold.
When you are sure the model is manifold, export it as an STL file. This is the most common file type used for 3D printing and is accepted by most 3D printing software.
Step 3: Decide How to Deal With Overhangs
Most printers cannot print onto a layer that does not have enough support underneath it unless it is "bridging" from one point to another.
On my model, the roof is the perfect example of this because it overhangs the rest of the tower. You can just print the whole tower with supports, but that takes more material, time, and effort.
Instead, I just cut my model into parts using Meshmixer and printed the top and the bottom separately. This made my supports smaller and also made it not a big deal when one of my prints failed because it was only one hour lost instead of 7. This also allowed me to print the model with two different resolutions, fine for the top where there was more detail and courser for the bottom where there was less detail. (Courser prints faster)
Step 4: Upload the STL File Into Printing Software and Slice
I used Repetier host because it was free and recommended for my printer. Click the "+" to add the file and then scale it to the size you want.
When it's ready, go to the slicer tab and slice the file with your favorite slicer and desired settings.