Might suggest
BB reverse curls with a thumbless (thumbs over, rather than under) the bar. Going thumbless with Dl's & chins also works well. Reverse BB curls are an excellent bicep builder, thumbless or not.
BB finger curls. Sitting, have the elbows/forearms resting on the legs, just curl a BB from the finger tips to a full grip contraction. Lower the bar down agin to finger tip position and repeat. Tend for higher reps fpr forearm work. Some do this with a Db, which may require more attention to balance.
For the whole of the forearm, a rope wrist roller (easy to make your self). Might try standing on a bench/box/ chair to allow a greater distance for the weight on the end to travel. Going to love the burn and the results gained. Raise fairly fast and lower rather slowly.
Many other strict forearm exercises to be considered. Pick one you think is best for your needs. Good Luck.