Below is a cut and paste from an email from our son:
Ok so here’s a few things about the horn button:
So I made the button CAD by measuring your existing one, taking a picture to overlay the TOYOTA logo, and sketching everything in a free online CAD software called Onshape.
The old button was cracked, but still good for taking measurements. I’ll attach an STL and STEP file for the button. The STL is what you could use for printing. A STEP is useful for importing if anyone wants to edit the file.
I printed the part on a Form 2 printer that I had at work. (
Form 2: Affordable Desktop SLA 3D Printer - https://formlabs.com/3d-printers/form-2/)
I used Clear resin:
Clear Resin 1 L - https://formlabs.com/store/materials/clear-resin/
25 micron print resolution
Post processing steps:
-90% Isopropyl Alcohol bath for 15min
-UV oven for 60 min
-Progressive wet sanding starting at 800grit going to 2000grit
-Rinse with isopropyl and water
-Block off triangle with painter’s tape
-Paint backside silver
-Remove tape, paint backside white
-Spray whole part with UV-resistant clear coat
Below are some photos which hopefully show the process.