The ornamental design for a beamprojector, as shown and described.
1. Beam projector
1.1: Perspective
1.2: Perspective
1.3: Front
1.4: Back
1.5: Left
1.6: Right
1.7: Top
1.8: Bottom
The broken lines shown in the reproductions depict portions of the beam projector and form no part of the claimed design; The shading lines in the reproductions are used to show the surface of the claimed design, and do not represent its surface ornamentation.