I got finally tired of using foam and tape to support the arms of Beogram 400x during shipping. A while ago I received a Beogram for restoration that came packaged with the original B&O arms support made from rubber. Believe it or not: I forgot to take a picture of it! But I copied the design for 3D printing at a later point and then I forgot about it.
Recently, I came across the design and decided to print it with flexible TPU filament. It worked very well: