Version A is tested, but not with the rings on the right.
Version B tested, changed the thread size for the small threaded gate to 13mm to get 12mm when printed.
Note: "this is not a safe hook to lift people or heavy loads!"
A Carabiner with threaded, the picture shows different versions but only two of them are tested, see pictures.
Version A is less complicated and only two steps to mount it. Alternatives with one, two and three rings are attached also for this version, but not tested!
After the print is made, cut off the supports. the safety lock hole and the gate axis will be a bit hard to turn them when inserted to each other in beginning, but just insert them, using a pliers( don't press hard the part with the pliers), keep the gate axis and turn the lock until they become easy to turn by hand.
Important: don't clean or drill the gate hole with a 3mm drill bit, this hole is meant to fit the small stick without glue, use a hammer and gently hit the stick as shown in step 2.(orange parts)
A quick test is made with a 14Kg load, the hook seems to hold fine.
The PLA under stress and temperature tend to bend or break!
Don't print the parts vertical position, the hook parts can be printed as the actual position in the files(horizontal), see picture below.
Tinkercad link to the hooks:
This settings are for reference only.
Printing temp.: 230C
Buikd plate temp.: 60C
Don't print it vertical
You can see this smaller version printed vertical.
The picture shows that layers will break easily when bent, in this case you can think about a layer of sheets placed over each others, that are easy to break when bent.
When printed horizontal, think about a bamboo or a bunch of sticks. that are harder to break when bent.The threads also are stronger when printed horizontally.