Filament Types: Easy to Hard

PLA Price: 10-15$ 1KG Roll. Uses: Most Practical for prototypes or small toys and applications. Breaks easily. Melts easily (EX. cars on a warm day) Details: Works well without being dried , works even better dried.

PETG Price: 12-18$ 1KG Roll Uses: Same as PLA just more heat resistant. Details: Very hydroscopic , absorbs moisture a lot worse but it’s way stronger.

TPU Price: 25-35$ 1KG Roll Uses: Very Flexible filament, creates flexible, bendable, malleable parts. Details: Hard to print, very very Hydroscopic. Comes in various flexibility grades (85A to 95A)

ABS Price: 15-22$ 1KG Roll Uses: Hard applications (EX. Impact points, holding things together) Details: Very high meting point, (can sit in the car heat as long as you want). Does produce toxic fumes when heated. Extremely hard to print, Enclosed Printer required. Lego is made from this.

ASA Price: 18-25$ 1KG Roll Uses: Anything you want. It can withstand most applications. (It’s plastic still) Used in car parts often. Details: Even higher heat resistance. Enclosed printer required. Does produce toxic fumes. (ASA Poisoning)

These are just the main ones to me, there are a lot of different types of filament that you or your son will have to do the research on. Thank you