One of my favorite for forearms is towel grip pullups. Loop a towel over a pullup bar and grip each of the ends and do pullups.. also the old school broomstick,shoestring and a 5 lb plate where u tie the plate to a broomstick with a string or light cord about 24 to 30 in long. Hold the stick handle with both hands palms down straight out in front of you and roll the weight up using rooling movements of each hand. Once you roll it all the way up, releases the slack n let it slide back down. That's one set. If u wanna take it further unroll it back down in stead of letting it unroll... reverse grip ez bar curls, Db hammer curls and this one as a finisher will smoke them forearms for sure!

Rice bucket training is something a lot of guys use for forearms. You fill a 5 gal bucket with rice and just dig your hands 1 at a time down to the bottom and back up. Farmer carries can help build up grip strength as can hanging from a pull up bar for time. You can directly work the forearms with dumbbells by resting your forearm across the bench and then moving the weight upwards. You need to do hand facing down, facing up and on its side thumb facing up to try and get all the different muscles.

Like press said deads. And shrugs. Pull ups. Nothing will build traps and forearms like those. Throw some hammer curls in wallah. All those wrist curl won't compare.

If you want great traps then in my experience nothing beats doing deadlifts - from the initial pull off the floor right up to lockout where you have your arms hanging down those traps are under constant heavy tension, I always have my best traps when I am deadlifting my heaviest both in singles and doubles/triples. I find they work better than when I went through a phase of doing loads of heavy shrugs in a power rack. Good forearms just come from lots of heavy lifting/pulling and not relying on lifting aids too much. For example on bench I never have worn or relied on wrist wraps to lock my hand/wrist in position which over the years I guess has helped me get quite good forearms and wrists considering I never do any arm or bicep work.

so for forearms, what i used to do is tie a string onto like a pipe or somekind of round thing thats long long enough for you to get both hands on. put the string in the middle(you might have to tape it to hold it secure so it stays in place when you roll the pipe) and on the other end of the string you tie it to a light weight say 2.5lbs-5lbs(i forget its been so long, i dont do this anymore) you do overhand rolls one hand at a time, then you can do reverse rolls one hand at a time. and as you do the rolls the weight will slowly reel up until you are out of string and the weight is up to the pipe, then roll it back down until the atring is fully extneded. its hard to explain. its called wrist rollers. look it up. i used to do it but i will warn you its painful but any forearm workout is gonna be painful.