Build -a- Mod is a DIY kit that provides you with all the parts necessary to modify your lenses yourself.


Why shop around for parts from website to website when you can Build-a-Mod and get everything you need from one shop? 


Modify your lens from top to bottom with the following:

  • Custom 80mm Slip on Lens Cap
  • 80mm Front SIMRING
  • Seamless Follow Focus Gear (MADE IN USA / LIFETIME WARRANTY)
  • SIMMOUNT EF Conversoin Kit
  • Rear EF Lens Cap


Each package will consist of the parts above.  We are constantly adding more lenses.  If you do not see your lenses listed, please let us know and we can work with you directly.


*If you're interested in purchasing Seamless Follow Focus Gears on their own, please visit our partners at  They're our exclusive provider and are industry leaders in seamless gears for lenses.


RESOURCES: (filter sizes, lens info)

Contax Zeiss Lenses

Leica R Lenses

Nikon Lenses

Canon FD Lenses

Mamiya Lenses

All Other Lenses