Here are a couple pics of a home made tounge muffler that will replace the factory silencer for my FP .35 ( it broke in a crash).  I used my bandsaw to make the cuts but you could do everything with a hacksaw,file and taps.

Take 1.5 inches of  Du-bro exhaust extension stock. I cut the sides down to reduce weight and left 2 ears that get drilled and tapped for the mounting screws. The open end is capped with a piece of aluminum angle from the hardware store, sealed with JB Weld and  retained with 3 small machine screws in tapped holes.
Drill 2 rows of 1/8 inch holes and you are done.

It weighs 23 grams with mounting bolts, the stock muffler had a couple chunks missing and no bolts it was 46 grams.
You can make 4 from 1 extension.

Thanks to Richard E. the NW Fireballs President- I had the blank cut already, and he graciously offered to take it to his shop and do all the drilling / tapping to finish it. I know it weighs 2X what some of the professionally manufactured units do- but the ready availability and low cost help offset the weight penalty.