You want the gullotine type (those used by traditional photo studios) or roller type. Whichever type, the best retail place to look at them is at the stationery shop in Funan, 2nd Level. That would be the best retail outlet for you to look at it; otherwise you will need to go for industrial suppliers; more troublesome (but may be cheaper).
Rotary Trimmer is for professionals, used to use one..:thumbsup:
can't remember where my late brother got it from, anywhere, did a Google search the Rotary Trimmer, two local distributors pop up.
btw, Lam Thong address is 11 Lorong 21A Geylang Road LAM THONG BUILDING, 388429, Singapore. walking distant from Ajunied MRT station, tho they are graphic suppliers, but photographers can also find a lot of interesting things.