Snap-through　bistability　was　widely　exploited　for　rapid　hopping　in　micro-electro-mechanical　systems　and　soft　robots.　However,　considerable　energy　input　was　required　to　trigger　the　transition　between　discrete　buckling　states　blocked　by　potentialwells.　Here　a　dynamic　buckling　mechanism　of　a　buckled　blister　constrained　inside　an　outer　ring　is　explored　for　eliciting　rotary　actuation　via　a　localized　change　of　curvature　in　the　blister.　Due　to　rotational　invariance　of　the　buckled　blister,　lower　energy　supply　is　required　to　initiate　the　snap-through　of　buckling　compared　to　conventional　bistable　mechanism.　The　controllability　in　rotational　speed　and　output　torque　of　the　bimetallic　blister-based　rotator　inside　a　rigid　stator　is　exhibited,　and　the　locomotion　is　demonstrated　with　two　elastic　rings　via　localizedpneumatic　actuators.　Withbroadchoices　of　stimulus　andmaterial　for　rings,　the　findings　illustrate　the　promising　potential　of　two　nested　rings　to　create　activemotions　for　diverse　applications　including　gearlessmotors,　peristaltic　pumps,　and　locomotive　robots.