Custom notehead creation - guidelines?

I’m designing a custom notehead set for extended techniques in a vector graphics editor. I will import this custom set into Dorico.
Are there guidelines regarding pixel dimensions of the existing standard notehead sets in Dorico? I would like to use these to create a template for my custom set.

If you have the wherewithal to do so, I would recommend that you put your new vector graphics into a font. You can copy and paste the noteheads from Bravura into your own font, then paste your own vector graphics in and match their position and size to the Bravura noteheads, then remove the Bravura notehead once you have everything matched up. If you need a free font editor, FontForge is available for Windows and Mac. There are other commercial font editors: we use both Glyphs (which Anthony uses for the icons in the user interface and for Petaluma) and FontLab (which I use for Bravura), and both work excellently. Glyphs Mini, the cheaper version, may well be sufficient for your needs.