Outside Ring

Now that I had the design planned, it was time to start work on designing each part on its own. I started first with the file outside_ring.scad (top image).

This part was very easy to design. I simply took the entire part from roundel_main.scad and kept only the bottom section and the ring around it. I did this by creating a cylinder that encompassed the ring section and another cylinder that plunged into the middle of it, creating the dish shape.

OpenSCAD users: Uncomment the last line in outside_ring.scad and press F5 to view or modify this part.

Inner White Ring and Sectors

Next up was the white_inner.scad part (second image). This part was made from the roundel_main.scad file with the thickness of outside_ring.scad cut from the bottom. This way, the height of the white_inner.scad part on top of the height of the white_inner.scad part would equal the total height of the part.

Then I kept only the area in the middle of the part (the middle of the roundel). I then subtracted two quarters of a circle on each side. This created the white_inner.scad part.

OpenSCAD users: Uncomment the last line in white_inner.scad and press F5 to view or modify this part.

Inner Blue Sectors

Then I created the blue_inner.scad part (third image). It was made from the same two quarters of a circle in the white_inner.scad part, but I kept out the intersection with the original roundel_main.scad part, with the bottom part (height of outside_ring.scad) cut off.

OpenSCAD users: Uncomment the last line in blue_inner.scad and press F5 to view or modify this part.

Letters

Next was letters.scad- B, M, and W (fourth image). These parts were far more complicated than I bargained for.

First, I had to find a font that matched the letters on the BMW logo itself. BMW has its own branded versions of Helvetica that are used for all company products and communications. Although I could have removed the font from a company press release PDF (not very nice), I emailed BMW politely about my predicament in hopes of procuring a copy of the font for non-commercial use. They were, unsurprisingly, not willing to help out

So I looked around on the internet to find a copy of Helvetica that looked similar to the logo's font. I found one, and the letters provided in the STLs are in a font that looks almost exactly like the logo's font. This font is a version of Helvetica and is freely available from this website under Helvetica Neue - Bold (direct link). It is also packaged with the OpenSCAD design files in the download.

OpenSCAD has the feature to use a font to write text in a 2D format. So I did that with the B, and then created and rotated the M, and then created and rotated the W. Then I squished them to fit and pulled them upwards to create a 3D letter shape. I then kept out the parts where they intersected with roundel_main.scad, and cut off the height of outside_ring.scad from the bottom.

OpenSCAD users: Uncomment the last line in letters.scad and press F5 to view or modify this part.

Black Top Ring

Finally, I created the part top.scad (fifth image). Because this part is the last piece of the puzzle, it's kind of a freebie. Simply put, it's the part that's created in the space of roundel_main.scad where the other parts aren't.

In other words, this equation describes the space of the part:

top.scad + letters.scad + outer_ring.scad + white_inner.scad + blue_inner.scad = roundel_main.scad

Therefore, this must be true:

top.scad = roundel_main.scad - letters.scad - outer_ring.scad - white_inner.scad - blue_inner.scad

That's really how this part is designed! It's just roundel_main.scad minus all of the other parts.

OpenSCAD users: Uncomment the last line in top.scad and press F5 to view or modify this part.