After seeing ThatSlacker's laser-cut ruler addition, I decided to do the same, but w/ 3D printing. You can use any two colors you like, but the best results I had was a dark base and swap a brighter/lighter color for the final layers.
See notes below if you've never done a color swap before. I'll also add links to the hardware I personally used in case you're unsure what type. It doesn't really matter though, as long as the bolts are long enough to go through the arms and tighten down with the fastener. I prefer torque tops with black finish, but that's purely personal preference.
Hardware Needed for Normal Version::
4 - M4 x 15mm bolts
4 - M4 nuts
Hardware Needed for Inlay Version
4 - M4 x 12mm bolts
4 - M4 nuts
The whole thing was rigid after the first assembly. The bolts didn't slide very well, and I was pretty underwhelmed. After loosening the tops and sliding the bolts up and down the arm lengths, it cleaned up the pathway, so now it works seamlessly.
Additionally, a request was made to recreate the inlay of the OG Angle Measuring Tool. These versions supposedly allow the bolt heads to sit flush. The measurements of these inlays would mean that depending on which orientation you placed this piece (short arm on top or long arm on top), the heads of the bolts would need to fit in the following dimensions:
Short Arm Inlay:
- Depth = 3.2mm
- Width = 7.2mm
Long Arm Inlay:
- Depth = 2.8mm
- Width = 7.6mm
The pause on both of these versions should be the same, since the total depth didn't need to be adjusted for the inlays. At a later date, I may make one specifically for the hardware I used, but these would be thicker, which may cause other issues.
Monoprice Maker Select v2
Resolution and infill shouldn't matter. Really up to you. I used the above listed settings. If you do use those settings with 3 solid top/bottom layers and 3 outline/perimeter lines, you can add the pause in the gcode at the following layers:
Short Arm: Layer 26 (Z = 4.168)
Long Arm: Layer 20 (Z = 3.208)
Depending on what slicer you're using and preference, you can handle this multiple ways. The easiest (and universal) is to cross section your model to find what height you want to swap the color. On mine, it was at the above listed heights. Normally, I'll swap colors when the base color, this time black, finishes the final 3 solid layers on the lines/numbers.
Once you know the height you want to swap colors, right click the gcode file and edit/open with a text editor (I personally use Notepad++). Search each layer until you find the height, and put the following gcode command under the layer: M0
You can use other commands, but this one is your basic pause command. Your extruder will pause at this layer and move up and usually to the bottom left corner. Do Not Manually Adjust the Extruder Position. Doing so will adjust the extruder by the manually adjusted amounts once you unpause.
This is how the gcode looks for the Long Arm:
; layer 20, Z = 3.208
; tool H0.160 W0.400
; inner perimeter
G1 X158.575 Y96.490 F4500
G1 Z3.208 F1002
G1 E0.0000 F3000
It's not necessary to put it as far down as I did, but it helps on other color changes, since unpausing the print will go to the last location. If you pause too early, it will sometimes leave big ugly marks before moving to the starting position of that layer. Hopefully this all makes sense. if not, you can find more info here.
One last trick I use is to turn the fans off on the last layer of the first color, and turn back on the second layer of the second color. I have no idea if it helps, but some prints in the past have lost the top color before. I know it can't hurt. I also try to swap colors out as quickly as possible. I use eSun cleaning filament between colors for quicker changes.