In this paper, a new painting robot using a roller for indoor wall painting had been implemented. The main criteria for the new design are simplicity, rigidity, stability, user-friendly interface, lightweight, speed, and cost. This robot will paint walls by using a roller fed with paint from a pump. The roller scans the wall vertically while the robot mobile base will move autonomously inside the room walls to finish painting. The robot consists of a differential drive base over which is attached a linear cascaded lift mechanism that lifts a painting x-y stage to fixed heights of the wall. The x-y stage then scans a fixed area of the wall with its tip fitted with a standard pump-fed roller. The design is made such that the heavier lift mechanism is subject to less motion and then less wear compared to the light x-y stage. The robot is implemented with simple control and user interface. Experiments showed that the system has good performance with a weight of 20 kg and a painting rate of 5 m2/hr.