Rear lens caps · STL / 3MF
Canon RF rear lens cap to 3D print
A twist-on rear cap for Canon RF lenses that you print yourself. It locks like a camera bayonet, prints face down without supports, and can carry your focal length on the face, so you find the right lens in the case at a glance.
Locks like a bayonet
Three claws of different widths sit in the lens neck in Canon's own layout, so the cap goes on one way only. Then turn clockwise (looking at the face) until a lug runs onto the stop.
Ramp and lock land
Each claw ramps down along the turn, then a nearly flat lock land holds the lug just before the stop. Resistance rises as you turn, and at the end the lug rests on a surface instead of an edge, so the cap sits firmly and wears less. Same settings as our print-tested mounts; the free fit ring confirms them on your lens.
Made for FDM printing
Face down on the plate, no supports. Vertical teeth or flutes hide layer lines, a 45° foot chamfer hides elephant's foot, and the face gets the finish of your build plate.
Your focal length or logo on the face
Optional: the focal length (zooms such as 24-70 too) or your own logo, as a flush inlay in a second colour or engraved 0.5 mm into the face if you print with one filament (tip: one wall on the first layer keeps it crisp). With a logo you print the same cap for every lens in your set. Inside, the mount code and the Focus Rings logo are engraved in the floor.
Fits
- Canon RF lenses (full frame) and RF-S lenses (APS-C)
- Weather-sealed L lenses: the rim stays clear of the rubber seal around the mount
- Third-party RF-mount lenses from Sigma, Tamron, Samyang, Viltrox, Laowa and others
| Mount | Canon RF |
|---|---|
| Outside diameter | Ø63.2 mm |
| Height | 16.7 mm |
| Room for the rear element | 14 mm below the rim, a little more than Canon's own cap |
| Grip | Module 0.8 gear (77 teeth) or flutes |
| Print orientation | Face down, no supports |
| Print time (slicer estimate) | about 37 min, about 14 g PLA |
| Fit test ring | Free, about 16 min |
| Files | 3MF (body + face inlay as one object), aligned STLs, printing guide |
Print times are Bambu Studio estimates for an X1C with a 0.4 mm nozzle and 0.20 mm layers. Not every lens has been tested: print the free fit test ring first.
Print and fit
- Print the free fit test ring in the generator. It is the bayonet zone only and done in minutes.
- Put the lens lugs into the gaps and turn clockwise (looking at the face) until it stops. It should turn smoothly and sit firmly.
- Print the cap face down on the build plate, no supports. Two-colour faces: keep body and inlay as one object and give each part a filament.
Questions
Which lenses does the Canon RF rear cap fit?
Canon RF lenses (full frame) and RF-S lenses (APS-C); Weather-sealed L lenses: the rim stays clear of the rubber seal around the mount; Third-party RF-mount lenses from Sigma, Tamron, Samyang, Viltrox, Laowa and others. Room for the rear element: 14 mm below the rim, a little more than Canon's own cap.
Has this Canon RF rear cap been tested on a lens?
Not yet on a Canon RF lens. The bayonet is measured from caps that fit real lenses, the lock uses the settings tuned in our print tests on other mounts, and every file passes a layer-by-layer support check. Print the free fit test ring first: it is the bayonet zone only, done in minutes, and shows on your lens whether the cap will turn on and lock.
Does it need supports?
No. The cap prints face down on the build plate. Every overhang is at most 50°, and the claws have sloped undersides that build up layer by layer.
Which filament should I use?
Rings without clamps and lens caps: PLA or PETG, 0.4 mm nozzle, 0.20 mm layers, your usual walls. PETG is a little tougher if the cap lives in a bag.
Why gear teeth on a rear cap?
They are the same module 0.8 teeth as our focus rings, so the cap matches your follow focus gear and grips well with gloves. The vertical teeth also hide layer lines. Prefer something smoother? Pick the flutes grip.
What does it cost?
One price per file, focal length and AirTag pocket included if you want them. The fit test ring is always free.