Errors creating .stl file I am trying to print a small model for a class project.

There were errors when I originally tried to export the stl file, which is here.
https://drive.google.com/open?id=1Xuo7fPLtYH7GmFApBSuaffNCXg-nyn-O
(Wasn't sure how to copy the error log else I would post it here). I opened it in slic3er and it appeared, but it slic3er was stuck processing the triangulated mesh. I took it to the print shop hoping they could help me but it did not show up at all in their slicer program.

I decided to start the model over, since it was just made from an svg file I made and shouldn't take long. Tried to do a boolean union operator between the base and the logo since you cannot have intersecting objects for prints, but it just keeps crashing every time. Found another stack exchange that had the same problem because of non-manifold vertices. I think I checked mine and found nothing. Tried to run the 3D Print add-on and did not see any errors with that.

Here is the current re-done .blend file. 
https://drive.google.com/open?id=1jK6VZ5eToYQe2SryE1z38dvz1iU-rTtk
In the blend file from the link above the main reason for problems with 3D printing is going to be standard cases of non-manifold geometry.

There are a lot of areas with overlapping geometry with multiple vertices in the same place:



These will cause errors because of interesecting geometry. It can be previewed with enabling Intersect geometry for real-time preview in the Properties shelf > Mesh Analysis rollout (available in Edit mode):



As there are many places with such tiny errors it's easier to fix them all at once; first off in Edit mode with all selected use Remove Doubles command to get rid of duplicated vertices. Note to set threshsold quite small, like 0,000001 as otherwise there will be some changes in the letters form (tiny changes though).

After ~1200 vertces removed run Ctrl+Alt+Shift+M or Select > Select All By Trait > Non-Manifold from 3D viewport header. There will be some vertices selected in the area in '8' digit:



There could be some overlapping faces left next to faces with inconsistent normals. Check if there are and remove doubles once again if needed; in general the only thing left is to recalculate normals there with Ctrl+N (or with all selected).