Buy and build or hire and buy

[curious aardvark]

it might be worth approaching a print bureau, with regards to getting the parts made from nylon.

3d printed abs is not great. pet-g is better, doesn't need heated enclosure, but is problematic to get the settings just right.

But then all filaments have their own particular quirks.

The qidi is by far the superior machine - also comes with hittemp extruder - currently at no extra cost and is just better all round.
I3 style printers are currently popular, mainly because the design can be solid (just don't get an ender 3) and it's really cheap to design and make.
But if it were me - I'd get the qidi and not bother with abs just go straight to working out how to use pet-g.
Pla is also seriously good - ignore all the archaic crap about it being brittle - I've always found 3d printed pla it to be stronger and tougher than 3d printed abs.
Americans making parts for cars always bang on about it needing to bear up under 70c in car temps and that's why they have to use abs - that kind of heat inside a car is not an issue in the uk :-)
Pet-g has a higher glass point than abs, and once you get a profile set up right - is really tough.
So is just better all round.

Then there is hi-temp pla.
2 types.
1) slightly cheaper you cure in an oven after printing, you have to factor in a slight shrinkage, but after curing that's good for over 100c.
2) just print as normal and is good for over 110c - not cheap, but impressive stuff.

Then you've got the pricey engineering filament types like ninjateks armadillo.
That's pricey, but really amazing stuff. A rigid polyurethane that prints as easily as pla (I know this as I accidentally used a sample of it instead of pla and it came out fine :-) The rigidity and toughness specs are off the charts and it's glass point is also much higher than abs.

One of the problems is that the 3d printing materials industry is churning out new filaments at a phenomenal rate while the user base is largely using the basic 3 and is - generally - stuck five or six years in the past.

I try and test as many different materials as I can and generally only make practical items.
So just bear in mind there are a lot of options beyond the basic pla, pet-g and the obsolete abs.

Design wise, it largely depends how your brain works. I use openscad, because my brain seems to only work in 3d. Just can't do 2d drawing by hand or mouse. I find openscad so much easier to use than standard design packages.

Tinkercad is also supposed to be very good - haven't tried it myself, but supposed to be easy to use - for a wysiwyg package.