NOTE - SEE "CAUTION" SECTION, BELOW
This is a replacement stopper for a "Cheeki" brand stainless steel water bottle/canteen. The threaded section has inner diameter 29mm, with the outside of the thread approx 33mm diameter and the flange 35mm diameter. Thread pitch is 4mm. You could scale it for other pressed steel bottles.
Note that the thread in the Cheeki bottle is pressed in the steel, and hence rather vague and coarse. Sigg, Optimus, Brunton, Primus, MSR, Snow Peak, and Kovea bottles all use the Sigg thread, which is a proper cut thread and requires a stopper with a proper thread profile, not the shallow flat form used on this stopper.
The bottle is sound but the original stopper broke, and it became apparent that the design was poor - the inside was hollow right up into the handle, with resulting inner areas in contact with the drinking water but pretty much impossible to clean properly. This replacement has a flat end, with no inner bits to clean. (Theoretically anyway - if the print isn't good or the material porous, it could be significantly more of a germ trap than the original, be cautious.)
See notes. Food grade PLA
Printing: designed to be printed without rafts or supports in the orientation presented, i.e. printed with the surfaces that are to be glued together touching the build bed.
Food safety: PLA is derived from edible materials and nominally non-toxic. In contact with typical foods it can leach a small amount of lactic acid, but lactic acid won't hurt you. However, the dyes in coloured filaments, and any additives used to change the properties of the material, might well be less than food-safe. I wouldn't recommend using any filament for the bit that screws into the bottle that isn't explicitly stated to be food grade. The handle part could be any PLA that looks nice, though.
On a related note, if your printer hot end isn't stainless steel, it might leach trace amounts of toxic materials into your PLA while printing. Finally, the printed result is unlikely to be glassy-smooth, far from it - the surface ridges typical of 3d printed parts represent an ideal substrate for bacteria to form. Now, nothing is free of bacteria in normal daily use, so giving it a good scrub with a brush and steeping in boiling water for a bit could well be enough to make it OK for water bottle use, but I'm not accepting any liability if you give yourself food poisoning using this design - read up on the risks and form your own opinion about whether the finished stopper can be used for drinking water.
A good starting point would be these articles:
My prototype used clear PLA from 3D Warhorse which isn't explicitly described as "food grade" but claims to be non-toxic, with REACH, RoHS, and MSDS Certificates.
Glue the two parts together with superglue (cynoacrylate)
Glue the two parts together with superglue (cynoacrylate) using short bits of 1.75mm PLA filament as alignment pegs in the holes provided. Obviously the top "handle" part can be made from a different coloured PLA if required.
I DO NOT RECOMMEND THAT YOU USE THIS ITEM FOR DRINKING WATER or any other beverage without researching and understanding the risks, which are yours and yours alone.
I consider that I have discharged my duty of care in this matter by drawing attention to the possible hazards that I'm aware of, below - there may be others, it is up to you to decide if you want to risk it.
I strongly recommend that you look into the food safety of your chosen material, your printer, the finish on the printed part, etc. Note that:
ABS is not food-safe.
3D printed articles are not smooth or inert, they are ridged and probably porous. Even a seamless item made from food grade PLA will likely be a germ trap, and it seems to be very likely to be extremely hard to remove all bacteria from the surface of any 3d printed object.
Hot beverages, alcoholic or acidic beverages, etc, may leach much higher levels of contaminants from PLA, and are more likely to increase microscopic porosity, cause general degradation of the plastic, etc.
Brass printer nozzles are not food-safe (they contain lead in concentrations beyond the 0.25% allowed in e.g. brass taps, pipework etc. used for drinking water) Likewise the nozzles used to extrude the material into filament for sale. And the brass toothed feed wheels. (The amount of lead transferring to the PLA would be miniscule, though (else the nozzle would disappear over the course of a couple of prints) and the amount transferring from there into any water in contact would be extremely small. Still, I accept no responsibility for any harm arising from the use of this design. )
Lubricants in the printer and dust settling on the filament reel can end up in the print.
See "Notes" section for some links to food-safety discussions.
- Commercial printers might be able to make one or other part of this in e.g. ceramic or metal.