I've been lurking and learning for years. I thought I would post this sign I made for the local Marine Corps League of which I am a member. The sign is made from HDU. The 3D I purchased from 3d machinist. I made the 3D from 3/4 HDU and inserted it into the larger frame. I have what I call a modified solsylva machine that I built myself. It cuts HDU good at 65" per minute and 50 on wood.
I know that is slow compared to a lot of folks but I've found that it makes for a lot less cleanup.