This adapter allows a tube to be run through the wall (or cap) of a container. This second version of my tubing bulkhead / panel fitting requires no additional hardware, though is less compact. The body and caps are printed in different orientations to overcome layer adhesion strength limitations, but it is probably a little less robust overall than the first version, which compresses the layers with bolts. Tubing is squeezed by small rings of material to clamp it in place and provide strain relief. No vents are included on this version, just drill a small hole in the container if one is required.

All required supports are built-in via bridging. After printing, just break through the single-layer bridging in the end caps. To help compress the tubing during assembly, there are conical ends the caps slide onto. Found this method was easier to control the lockup position of than using tapered threads.

To install:

1) Use the drilling template to drill the centering pilot hole in the container or cap. This hole is for the adapter to pass through.

2) Dry fit the adapter on your container, and sand the bottom of the cap or the adapter flange if needed to adjust the fit so it is tight. 

3) Thread the tubing through one of the end caps and then fit the two adapter halves on your tubing, leaving the appropriate amount extending past it. For larger size tubing, it may help to warm it up first. Thread on the other end cap and then tighten them to compress the tubing, then remove the adapter again. A vise of pair of pliers may help. Doing this before installation in your container will ease the process by pre-compressing the tubing. Depending of your size of tubing, you may be able to get away with removing only the cap that goes on the outside of your container.

4) Feed the tubing through the center hole you drilled in the container or cap, and insert the adapter and put the caps back on again and tighten. Be sure to add sealant under the outside cap  and between the adapter halves if making an unvented connection and a seal matters.

You can create your own adapter with any dimensions you want in this Onshape document. No account is required. The default values are for ¼" ID, 3/8" OD tubing. This is the model that is included in this listing, as Printables requires one.

The adjustable parameters (in the upper left of the Onshape page; you may have to scroll or expand this section to see them all) are:

Panel Thickness: How thick the wall the adapter will go through is. Better to make this a little too small, as you can lightly sand the cap or flange to adjust the fit to be looser.

ID: The inner diameter of the adapter. Set slightly smaller than the hose outer diameter.

Ring_Protrusion: How much the two grip rings protrude into the tubing. They grip the tubing.

Drill_Diam: What size hole will be drilled into the container/cap for the adapter.

Thread_Len: What length of thread will be used for the end caps.

Cone_Len: What length of cone to help compress the adapter when putting on the caps. Slopes at nine degrees. If you need a really short adapter and pre-compress the tubing before final assembly you can probably omit the cone entirely.

Body_Len: Length of the body of the adapter. Adjust to have enough flange to press against the container wall, and also to position the inner cap to be easier to attach (mainly an issue for attaching to bottle caps, container walls can have a smaller body length).

Flange_Lip_Width: How large the flange that bears against the container wall should be.

Cap_Clearance: Clearance amount for the threads of the caps. Default is 0.3 mm, but I got 0.1 mm to work well on my P1S printer, so try a couple sizes if you want a snug fit.

Cap_Thick: How thick the walls of the caps should be.

Cap_Wrench_Flat_Size: Size of flats on the caps used for tightening (for small tubing, hand tight may be adequate).

Cap_Hose_Hole_Diam: Size of hole in the caps to allow tubing to pass through.

Layer_Height: Layer height for cap bridging. Default is 0.2 mm.

Template_Diam: Outside diameter of centering template (mainly meant to drill caps).

Once you've set all the parameters, right-click on the models you need (lower left), choose “export” and select the download format (most people will want “stl”), and finally hit the second “export” button.