After getting these pieces all spec'ed out and made, I had them printed at the Thinkhaus Hacker Space in Hamilton, Ontario (http://www.thinkhaus.org
).It took about 60 minutes to design, 80 minutes for them to print out these pieces for me, and then the following day another 5 minutes to realize I had screwed up.
I incorrectly added the LED height to the diameter of the piece, when I should have been adding it to the radius. This made the slot for the LED half as big as it should have been with no way to get it in.
Thankfully, it was a 3D printed piece, and very small and didn't use up too much plastic and fixing it took no time at all. As I had saved the part file, all I had to do was go in and double the distance for the LED and it was fine. It took another 5 minutes to make the changes and then again get them printed out.
Also, after talking to the people at the ThinkHaus I found out I had wasted a fair bit of time hollowing out the inner ring all the way around to "save on plastic". 3D Printing software, specifically slic3r in this case, has the option to set the fill density of the part. As this wasn't a structurally significant piece; there would be minimal load on it, it would actually be easier to print accurately if it was entirely filled in except where I actually needed the slots, and to set to a 10% fill in the software. This used a lot less plastic and was easier to print since the software made the voids to save on plastic, instead of me guessing what would be easiest, and in this case, being wrong.
In short, 3D printing is really rapid prototyping. Instead of hand machining these pieces out which would have taken days, especially with my mistake and having to redo them, 3D printing easily saved me a lot of time, and also expense, as in this case the amount of plasitc used was minimal.