All of them are a cylinder sculpted with multiresolution modifier. Here is what I have:
You can paint the holes with transparency. Basically, as you already did. Bake the normal map from the Multires and then texture the accessory. Use the alpha channel (or create a separate mask image) for Alpha slot of the Principled BSDF (or use a Transparent BDSF and a MixShader). Add some metal rings. That's it.
I had made something similar. Looks like this: