Fully parametric lens (tripod) collar, Arca plate

WARNING: Found that this file does not work properly with current Fusion versions anymore. You may still try it, but if strange things happen when editing parameters, I will not be able to help...

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Note: I've designed a second version for this lens collar which features more parameters but is more prone to “colliding” parameter values - so I decided not to replace this one but upload both parallelly, and recommend to download both to cover most every case of application.

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Ever needed an STL to print a lens collar? If so, you may have noticed that for some reason there are not two lenses in this world that are content with the same collar. Searching the web, you'll either find a collar made for that specific lens type you need it for, or you'll find nothing you can use at all. Even parametric models don't offer the settings you need…
Well, hopefully these times are over now: With the F3D file you can download from this page, at least every lens collar's dimensions that I have ever seen are fully reproducible. With a little subsequent work even exotic collars (for lenses that were never meant to be used with a collar…) can be made.

This is a lens collar that can be massively edited in Fusion by just typing in a few variables. Available features include variable inner and outer diameter, optional variable inner groove or tongue, stability and center of gravity/balance control, and variable height and depth.

Due to the variables' versatility I decided to use a two-part design. A one-part design of course would be more convenient, but could never be that versatile (since it's only applicable if it can be slid on). A hinged design would be versatile as well as convenient but wouldn't be rigid enough if 3D printed.
In exchange for this little inconvenience you get a parametric design that allows for any adjustment needed to make the collar fit virtually any lens (that can be used with a collar).

Additionally I decided to do without a tripod thread for the simple reason that, if a tripod thread is needed at all (the Arca style dovetail is a far better mounting base in any respect), there is no universal rule where to place it. I mean - you have the Fusion file, don't you? So, if you think you need a tripod thread, place it whereever you want.

Instructions:

If you open the F3D file in Fusion, you get a window looking like this:

Note that in the timeline there are two groups of actions and the timeline cursor (marked with a red arrow here) stands between them, meaning that the second (right) group currently is not used. This is fine if you plan to print the lower part in one piece (with the Arca plate protruding to the front only). 
If, however, you need to extend the Arca plate to the back as well (for balance reasons), you have to do two things before setting parameters:

(1) In the “Bodies” section of Fusion's file browser there is one body called “Support Foot” which is set to be invisible. Switch this one to be visible.

(2) Move the timeline cursor (red arrow) to the right.
Now, two things have changed (both marked with blue arrows in the screenshot above): The Arca plate has been extended to the back using a separate printing part, and two screwholes including head and nut seats have appeared.

Obviously, it doesn't make sense to perforate the collar's foot if you don't need the screwholes, so if you don't plan on using the “Support Foot”, keep the timeline cursor between the two action groups (where it initially was).

Now that you have set the basic type of collar to produce, it's time to measure your lens' (or tube's) dimensions and fill in the parameters that need to be changed. This is done in the parameters list (found in Fusion's “Modify” menu, named “Change Parameters”).
This is the full list of user parameters:

You can simply play with these values to find out what they do, or read a more detailed explanation here:

MainDiam, MainThick, and MainDepth: These are the parameters that define the dimensions of the actual collar ring.

• MainDiam: This is the most important value, the inner diameter of the ring. Measure your lens' diameter and add about half a millimeter.
  Applicable values range between 20 and 800 mm.*

• MainThick: This is the ring's thickness. It does not depend on the lens' measurements but only on the desired stability (the thicker, the more rigid).
  Minimum value is 1 mm (while sensible values range between 4 mm and MainDepth value).

• MainDepth: This is the ring's depth. For maximum rigidity, measure your lens' maximum coverable area (excluding aperture and focus ring etc., of course) and use this value.
  Minimum value is 8 mm.

NotchWidth, NotchDepth, and NotchOffs: If you are retrofitting a lens that originally was not meant to be used with a collar, you can most likely ignore these parameters. If however, you are making a replacement collar for a lens that is meant to be used with a collar, your lens most likely either has one or more guidance pin(s) like this…

…or a guidance groove like this:

These pins/grooves have the purpose of keeping the collar in position while rotating the lens and camera. Of course, this has to be respected in the collar's param settings by adding either a groove or a tongue:

• NotchWidth: The width of the notch (either the pin's width plus about 1 mm or the groove's width minus about 1 mm).

• NotchDepth: The depth of the notch (either the pin's height plus about 0.5 mm or the groove's depth minus about 0.5 mm as a negative value). This value determines if your “notch” will be a groove like this…
  

  
  …or a tongue like this…
  

  
  …depending on its algebraic sign: A positive value will result in a groove while a negative value will result in a  tongue.

• NotchOffs: The offset of the center of the “notch” from the center of the ring. A positive value will offset the notch toward the front of the lens while a negative value will offset it toward the camera.

For some exotic applications (mirror lens? Who knows…) you can even use the Notch parameters to create a collar with a step in diameter like this:

After defining a notch, it is advisable to set a slope (bevel) to the edge that will be overhanging when 3D printing (I can't predefine this in the file unless I limit NotchDepth to either positive or negative values).

FootHeight, FootLengthFront, and FootLengthBack: These values determine the dimensions of the Arca plate and its connection to the ring.

• FootHeight: This is the height from the lower edge of the lens to the lower plain of the Arca plate. Of course, the lower this value is, the more stable the tripod mount will be, so stick to the minimum value if possible. But in some cases this value has to be modified to a) allow access to the lens'  or tripod's controls, b) allow for mounting/unmounting the camera (bayonet rotation) or c) compensate height differences (e.g. if mounting a camera/tube/lens set to a rail).
  Minimum value: MainThick + 4 mm if making a foot without screwholes, or 
  MainThick + 12 mm if making a foot with screwholes.

• FootLengthFront: This is the length of the Arca plate that is added to the MainDepth in front of the collar.
  Minimum value is 11 mm.*

• FootLengthBack: This is the length of the Arca plate that is added to the MainDepth behind the collar as a separately printed part. This additional part has to be used only if it is needed for balance or to partially “unburden” the plate's front part (in case of heavy load). Don't forget to activate the screwholes in the file's timeline if you want to use this additional plate.
  Minimum value is 6 mm.*

*  These values/ranges may be exceeded/underrun without any critical (mostly just cosmetic) consequences. Just inspect the model closely after doing extreme modifications: If just some bevel or fillet can't be applied, this most likely does not affect function. If, however, screwholes disappear or additional bodies are created, you have overstepped the mark.

So, now that you have set all parameters needed, export the two/three objects you have created as STLs and print them.

Printing instructions

Obviously, I have no idea how your collar looks or how wisely you chose dimensional values, so I can only say some general things about slicing and printing:

• After exporting the STL files, load them into your browser. The “Upper part” and “Lower part” will have the correct orientation for printing right away while the “Support Foot” (if you use this one at all) has to be rotated by 180° to lie flat on the printbed.

• Use some sturdy material. Of course, you can print a lens collar using PLA, but this means you will need about twice as much thickness (and material) as you would need if using PA-CF. Using CF or GF reinforced filament is generally a good idea but means that (due to the prints' rough surfaces) you will have to do quite a lot of sanding after printing.

• In case of doubt, use 100% of infill. I can hardly imagine a plastic collar being too sturdy to fulfill its purpose.

Assembly

Assembly is quite obvious: You need two M3 flathead bolts of at least 10 mm length and two M3 nuts. Press the nuts into the corresponding cavities in the lower part, use the bolts to connect both parts.
If you are using the support foot, you need two additional M3 bolts and nuts for this as well. The bolts' length in this case depends on the parameters you are using (MainDepth x 0.8 + 5).

If you have any complaints or suggestions, please use the comment function. This was the first time ever that I made a parametric file with multiple variables that influence each other, so I'm a little curious about how well I've done.