Throwing the bean bag. Start with a bag that is so heavy you lose finger strength before the 10nth catch and practice until you pass 100.
There are many dif kinds of throws but since I can’t show you just be creative.
-behind the back
-over the shoulder
-under a kick
-straight up
-etc…
Besides what ged mentioned already- forearm curls (we used to have a plate tied to a small stick and we rolled the plate slowly up, then slowly lowered it…massive burn in the forearms, plus ancillary fatique in the shoulders), when you regularily workout your back muscles with progressive weight resistance, your forearms will grow. Why? 'cause you are constantly squeezing (exerting) with your forearms for added grip strength necessary to move big weights. This is why you see wrist straps used, this helps circumvent forearm fatique prior to.. say back muscle.. the intended muscle group fatique.
If you practice Hung gar, try doing the kiu sau section of Gung gee a hundred times. Or if you are advanced, the dragon section from Supyin and all of the iron wire. If not, try this:
Extend your arms in front of you palms facing up.
Open and close your hand as fast and hard as you can for 1 minute.
After a minute, turn your palms facing down and repeat.
While this will not build mass, it will build gripping power and overall strength in the forearms and hands. You arms should feel like lead weights after this exercise. If not add an additional minute to each exercise.
those hand grips won’t build mass but will give nice definition
“You can’t see it if you blind but we will always prevail (true)/Life is like the open sea, the truth is the wind in our sail/And in the end, our names is on the lips of dying men/If ever crushed in the earth, we always rise again/When the words of lying men sound lush like the sound of a violin/The truth is there, it’s just the heart you gotta find it in” - Talib Kweli
Here’s a great one…get a length of round wood, as thick as you can handle in your hands. Drill a hole in the middle of it, tie a fairly long rope (all the way to the floor if you want) through the hole and attach a weight on the other end. Then roll the weight all the way up to the stick and all the way down with your arms extended, using only the strength of your forearms and wrists. Then reverse, all the way down. Vary your routine (i.e. the direction you use up and down as concerns wrist rotation).
FEEL THE BURN!
We are trained in wushu; we must protect the Temple!