Journal
3D printed body caps for Canon EF, RF and Sony E: what to know before you print
Berni · 30/10/2026
A body cap is the least exciting part in your bag, right up until it's gone. Here's how the printable body caps on Focus Rings work, what they're good for, and the one thing I want you to do before you print the real thing.
Body caps disappear. They roll under the van seat, stay behind on a camera cart, or end up in the wrong case on the wrong body. The original replacement is cheap, but it's also plain black and anonymous, and when you have two or three bodies on a job, anonymous isn't helping.
So I made body caps you print yourself, for Canon EF, Canon RF, Sony E / FE and a few more mounts.
It clicks in like a lens
The cap isn't a push-fit plug. It carries the lens side of the bayonet: lip, neck and three lugs. You line up the mark with the camera's mount dot, insert it, turn it until the camera's locking pin clicks in, and the lens release button takes it off again. Same movement as a lens.
It also doesn't reach deeper into the camera than a lens's own bayonet does. On the Canon EF version the back of the lugs ends 5.8 mm behind the mount face, on Sony E 5.15 mm. Each product page lists the exact numbers for its mount.
Your label on the face
The useful part: you can put a short label on the front, up to 7 characters. A-CAM, B, FX6, whatever your crew calls the body. Or your logo, or the mount code in big letters. It goes in as a flush inlay in a second colour, or engraved into the face if you only print one filament. There's also an option with an AirTag pocket, for the people who have lost one camera bag too many.
Printing it
The cap prints face down, so the face gets the finish of your build plate. The lugs would otherwise start in mid-air, so the file brings its own break-off supports under them. Keep the slicer supports off and peel the little arcs away after printing. According to the slicer estimate, a Sony E cap takes about 25 minutes and roughly 11 g of PLA, a Canon EF cap about 28 minutes and 13 g.
The honest bit: print the fit test ring first
I measured the bayonets from parts that already fit real cameras: for EF, a body cap and an EF adapter; for E, a body cap and an E-mount adapter. Then I printed the caps and put them on actual bodies. Canon EF and Sony E are print-tested on a camera now. So are Micro Four Thirds, Nikon Z and ARRI PL, if you shoot those. Canon RF isn't yet. That one is still measured, not fitted, and the RF page says so.
Tested on my cameras with my printer still isn't tested on yours. That's why every paid file comes with a fit test ring: just the bayonet zone, done in about 10 to 12 minutes. Print it, put it on your camera and check three things. Does it go in? Does it turn with even resistance? Does it click and sit without play? If yes, print the cap. If not, you've lost ten minutes and a few grams of filament instead of a whole cap.
Your printer and your filament change the fit as much as my numbers do. A test ring tells you more than any spec sheet, including mine.
Which cameras
- Canon EF: EOS DSLRs, full frame and APS-C (EF-S bodies take EF caps too), EF-mount cinema cameras, and adapters or speed boosters with an EF mount at the front.
- Sony E / FE: Alpha bodies, full frame and APS-C, E-mount cinema cameras like the FX3, FX30 and FX6, and older NEX bodies.
- Canon RF: RF-mount bodies. The full list is on the RF page.
Body caps cost €3.90 per file. While you're at it: there are matching rear lens caps for the other end of the problem, and the Canon EF rear cap is free.