Screws and Bolt VDM Brush
This is a vector displacement map brush for Zbrush 4R8. These are not just alpha stamps but use the new VDM Chisel Brush feature added in Zbrush 4R8. You can adjust the Z intensity slider to reduce the effect. I'm giving this out as a freebie but donations are appreciated. Enjoy!
Load through the brush palette or copy the file to this path: C:\Program Files\Pixologic\ZBrush 4R8\ZStartup\BrushPresets