This is a straightforward tube holder to be attached to some furniture. The standard sizes provided for the tube are for the 18mm outer diameter tube of oxygen tubes like the ResMed SlimLine tube or their mask tubes and the clip to be attached to the furniture is sized for an IKEA headboard. For other dimensions of tubes or furniture, you can parameterize the provided OpenSCAD file.

I printed this with PETG and 0.2mm layer height. No supports are needed and there is almost no space left for infill anyway, such that this setting is also totally irrelevant. In fact, I just increased the perimeters to 4 to use perimeter walls throughout the whole object, which in my opinion makes the result look better when printed with transparent filament.

Note that if you print this with more stiff filament, like PLA you might want to shorten the clip noses a bit since the clip might otherwise break when you try to attach it to your furniture.

This model is technically derived from the more complex design https://www.printables.com/model/173643 I did before.