You have two options to become a replica manufacturer:

1: Opening a company, with its factory, its R&D, its distribution network...

2: Or home-made

Building home-made replicas has its risks, and we don't think that Leng Kah Shenghad the intenion to commercialize. He's the one who built Airsoft Tiger111hk:

It's a cool experiment and do not think that it is so crazy, there are very cool replica weapons made out of wood such as these: