Ok, I'm new here and building a Mendal. I have a basic questions re the hotends. What should I be looking for in a hot end. i.e. a 1.75 or 3mm material and a .2 or.5mm nozzle. Any recommendations on good / bad sources?

1.75mm
    Pros:
        Requires less torque, so works with a direct drive (gearless) extruder.
        Requires more steps/cubic mm of extrusion, so produces more precise extrusion.
    Cons:
        Costs more (by volume) than 3mm filament.
        With a bowden extruder, print quality is compromised because the filament is springier.

Personally, I use 3mm filament, and see no reason to pay the extra cost for 1.75mm filament.

.2 nozzle
    Pros:
        Extrudes a finer line, making more precise prints.
    Cons:
        Extrudes a finer line, making prints take considerably longer.
        Requires a higher torque extruder motor.
        Clogs easily.

I'd start with a .5 nozzle, and switch to a smaller diameter when you find that .5 is limiting you.

For U.S. hotend suppliers, I suggest MakerGear.com and hotends.com.

In Europe, it's hard to beat arcol.hu.

Thank you, sounds reasonable, so I'll go with 3mm filament and a 0.5mm nozzle.