You need:
A four foot length of one or one and a half inch diameter PVC pipe
PVC caps to fit both ends of the pipe
Glue suitable for plastics and wood
Quarter inch dowels
A Dremel tool with cutting disk and sanding attachments
A drill with a quarter inch bit
Plastic beads
Use the Dremel tool to cut your dowel into pegs of a length that is the diameter of the PVC pipe plus the thickness of the pipe. You will need about 50 of them.
Start drilling holes in the PVC pipe about two inches from one end. Drill each hole an inch down and an eighth of the way around the pipe to create a spiral of holes down the length of the pipe.
Dip one end of a peg into the glue and push it through the hole to stick the glue end against the inside of the pipe. Continue until all holes are filled.
Allow the glue to dry
Use the Dremel sanding attachment to sand the ends of all the pegs so that they are flush with the surface of the pipe.
Glue one end cap onto the pipe and allow it to dry
Pour beads into the unsealed end of the pipe. Adjust the amount of beads so that they fall over the dowels easily and make the desired rain like sound.
Glue on the other end cap.