A tutorial by Stupid Airsoft demonstrates the process of modifying a Hera CQR Gen 2 front grip for use on an airsoft rifle. He focuses on changing the color of the grip from its original shade to black using a dyeing method instead of spray paint. This approach is chosen to prevent the color from wearing off in high-friction areas during use.
An overview video by the ZUMISAVA Airsoft Channel showing the L5M LFM-910 P90 Front Grip made in Japan. This can be attached to the P90 airsoft guns and it may require some filing as there are some burrs when it was 3D printed. Check this out on Amazon Japan if it is already available to order.
AirsoftTech.dk shows the front grip he made for his M249 Para AEG... "I have an LMG, the M249 Para... I'm really happy with it, but the front has one major drawback in airsoft. Theres no rail to put on a front grip :-( . So I pulled up my sleaves and got to work. I created an adapter that i could attach a rail to.
Do you want to see how I did it? Well, take a look here."