A 250-pound woman stuck up a Staples store on the Upper East Side — tossing her weight around to intimidate frightened staff before making off with almost $3,000, police sources said.

The larger-than-life lady robber walked into the print-and-copy shop at Second Avenue and 66th Street at 6 p.m. Sunday as the store was closing, the sources said.

At first, the suspect, described as a 5-foot-11 black woman in her 20s, asked for help with printer ink.

But once the shop was empty of other customers, the corpulent crook allegedly whipped out a small firearm and demanded the dough.

Meanwhile, cops said a stick-up crew of four young men have robbed three other Staples in Manhattan on at least seven occasions for computer equipment.