A rotary trimmer for cutting and/or trimming paper and related sheet material is disclosed. The rotary trimmer comprises a trimmer housing having: (i) a first end portion; (ii) a second end portion; and (iii) a cutting platform having: (a) a first platform; (b) a second platform; and (c) a base platform. The first and the second platforms are pivotably connected at least indirectly to (1) the base platform; and/or (2) the first and the second end portions. The rotary trimmer further includes a blade carriage guide disposed between the first and the second end portions and a blade carriage having one or more cutting blades, and slidably mounted to the blade carriage guide wherein the blade carriage can slide along the blade carriage guide to cut and/or trim a sheet or sheet-like material positioned on the cutting platform. A method of using a rotary trimmer is also disclosed.