Since these crustaceans have little fat, can I make scented oils by boiling them in oil?

I wouldn't boil them, they would just deep fry imparting little of their scent. Maybe try a slow cooker with your crustaceans and keep it at a low heat.

Since lobsters, crayfish and shrimp don’t have any fat, to speak of, how are lobster, crayfish and shrimp oils made? I see them offered at many trapper supply dealers.

I thought they were synthetic but dont quote me. Thought shellfish is too.

shellfish is synthetic

tincturing in mineral oil is one way for crawdads. dont cook it

Danny, do you crush and allow to ripen a bit before tincturing?

Crushing them is good. I have always wanted crawdads fresh. Only used them for coons. Best use I found for them was to run through a grinder whole and fresh. Thaw them as needed. Best coon pocket set bait I ever used. Heard about mineral oil tincture from Rich Kasper. Like you I wondered where the oil came from since crayfish have no fat. The oil I made and the oil I have bought held no candle to ground whole and fresh. I have caught coons on leftover shrimp from drifting for channel cats. They work. Never tinctured any after being disappointed by the crayfish oil.

It isn't a fat rendered odor from the crawfish or shrimp that is being extracted, it is the natural body odor essence of the creature that is naturally embedded within it.