favourite wrist flexor strengthening exercises

[niqaeli]

So I keep meaning to get a rice bucket and otherwise do wrist/grip strengthening exercises but I keep running into a really oddball problem.

Which is that everyone who's interested in improving grip strength this way pretty much assumes -- not without reason, to be fair -- your wrist extensors are relatively weak compared to your flexors and focuses much more on strengthening them.

I just have literally the reverse problem. My wrist flexors are relatively weak compared to my extensors, and I'm really feeling it when I go climbing (or do aerial). (The tl;dr version of how the fuck you get to this really weird place, strength-wise, is: over ten years as a massage therapist.)

So! Does anyone have exercises for the flexors, specifically, that they're fond of? Variety especially would be good; I get bored of conditioning super quickly if I don't have different things to cycle through.