Don't ask me what inspired this, as I have no idea. I'm just going to detail the process on how I got this from an SVG to a 3 colour 3D print using FreeCAD.
It turns out there's a list of UK road signs in SVG format. Simply download whichever sign takes your fancy and follow these steps to make a model using FreeCAD.
Design
First, do the usual and create a new document with a new body. Then go File->Import and select the SVG file, then click on SVG as geometry followed by Select.
When you import the SVG there may be a whole load of redundant paths. Select and delete them.
Next we select the Draft workbench. Highlight all the remaining paths and select the catchily named Convert bidirectionally between Draft and Sketch objects tool.
Drag the resultant sketches in to the body. Pad largest/outer triangle 3mm.
Move inner triangle and graphic sketches up 1mm on the Z axis.
Pocket inner triangle 2mm in the reverse direction
Pad graphics sketch 1mm
This next step is optional, but because I wanted to turn these in to a keyring I put in a 6mm hole. I made a sketch on the topmost face and to get the hole in the right place I selected the 2 b-splines to get the curvature, put in a construction circle, constrained it to the 3 points from the b-splines, then put a normal circle and constrained the 2 centre points of each circle.
Pocket to finish the job. I made the hole 6mm here to scale in the slicer, instead of scaling the model in FreeCAD because I might want to use the larger size, sans hole, later.
Now down to the printing. This may differ depending on your slicer, but I use Cura. I loaded up the model. Scaled down to 50% on the X and Y axes only. I kept the Z axis at 100%. With this the keyring hole will be 3mm.
Next I added the Pause at layer height scripts. This will be used to change the filament for each colour. Layer 1 is white, layer 2 is black, and layer 3 is red.
I printed the keyrings in PETG, for UV resistance, using a 0.32mm layer height. This gave me a quick print with 3 layers per colour. The sheep pictured at the top was "ironed", train below was not. I was worried that ironing PETG, with it being very stringy, would be very messy, but it wasn't too bad.
