A device like this might enable the same ROM exercise at about half the cost:
https://www.amazon.com/gp/aw/d/B008U9ZQSE/ref=pd_aw_sim_sbs_200_of_12?ie=UTF8&psc=1&refRID=FKC6YQJZX8KVKSDD4XHJ
Haven't tried it, but as PMTS skiers need to practice CA in a narrow stance, a single disc device might be sufficient (optimal?).
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More advanced students could perform hip ROM stretches while balanced on one (stance) foot and tipping the other (free) foot. CA and Tipping are closely integrated movements, so this would reinforce that connection.
Thoughts?