I need gaiters for my 1944 lorry rear axle swivel joints,

[Dozzer]

Be wary of filament printing, I know polyurethane sticks to PETG like sh1t to a blanket even with mould release agents.

Probably as much to do with later lines than chemical bond.

I use resin prints for my moulds

SLA would be nicer, but dont have. Wouldn't use bare FDM for moulding, probably best to cover with very fine car body filler, smooth then spray/cover with epoxy resin, lot of time its the tiny layer lines that make things stick.

Making simple male and female cavities, then using a 70 - 80 shore room temp silicon rubber RTV maybe best option, we used to make moulds for fingers on the pick & place systems on assembly lines, you can buy 1 or 5ltrs of RTV and dye it what ever colour you want, we used to make them bright orange so you could see if they had pinged off.

 

[Matchless]

@Matchless
What is the diameter of the axle tube where the gaiter fits?
What is the diameter of the hub carrier where the gaiter fits?
If there is any offset between them how much?
What is the maximum articulation of the hub carrier wrt the axle tube?

4", 8" a fair bit but will be limited by moving the bump stops 15-20 degrees at present, maybe, there is a 1/2" offset ish, shown in the most recent pictures,

 

[Matchless]

Designing the joint will want a bit of thought. Maybe that's the next bit for us all to muse over

The joint as original has a flap sewn to one side of the joint, flapping on the other until bolted together, I thought for ease of manufacture just cut the gaiter and then stick / glue a strip of suitable material to one half and bolt as per original, would not be any benefit in trying to mould it as part of the gaiter,

 

[Hood]

....

Generally the liquid rubbers are polyurethane, not particularly strong in tear resistance and vacuum degassing normally required.

I was curious how strong the PU I used to make the boot for the side stand was.
Leftovers from the mixing tub, thickness varied between 1 and 2mm.
Gripped it in mole grips, held one in a vice and the other I attached some stainless flanges that weighed approx 6.5kg , left it suspended for about 4 hrs and still was fine and went back to original dimensions once removed.
I was expecting if it was going to tear then it would be where the mole grips were clamping it but all was good.

Couple of pics.

 

[daedalusminos]

I'm not saying it's not strong but once a tear starts it will 'readily' propogate albeit in my experience not so much as silicones. It's worse if it's not vacuum degassed as it tends to be full of microscopic bubbles.

I would hope the OP is considering 3D printed moulds, it's the perfect solution to the problem.

 

[oldbikedavey]

I'm not saying it's not strong but once a tear starts it will 'readily' propogate albeit in my experience not so much as silicones. It's worse if it's not vacuum degassed as it tends to be full of microscopic bubbles.

I would hope the OP is considering 3D printed moulds, it's the perfect solution to the problem.

Leather has to be pretty good if they wrap cows in it.

 

[Agroshield]

...for ease of manufacture just cut the gaiter and then stick / glue a strip of suitable material to one half...

It is the gluing that may be difficult. Plastics and rubber are hard to stick together.

That said, making it as one piece with integral flap would be difficult as the flap underlaps one half, so any mould would need to be non-circular. Maybe a helical mould so the unflapped side overflies the other part, with a thin separator between.

 

[Dragnet]

Leather's one of the great inventions (discoveries?) of civilisation. If the last one was from 80 years ago I'd be tempted to pursue the leather route! My first port of call would be to the cobbler in the market. Even if he can't do it, he'd be able to recommend someone in his circle of leatherworking acquaintances who'd be able to help, or pass you on further. Presumably they could re-use the existing fastenings and fixings. There's a UK leatherworkers group on Facebook here you could ask.