Hey, just wanted to share a little project i did myself. Basicly what i did was drill a mold into wood and fill it up with regular silicone to create custom grommets. This is the first iteration and i will probably go on to make a mold out of 2 parts. Here the pictures of the process. Drilled the holes into the wood. Filled the holes up with silicone. First one out. Took some take to loosen them out ot the mold. The two part mold will resolve that problem, also it will make it possible to have a flange on both sides. and here are all of them. 6 are for 12awg and the bigger ones are for 10awg.
the DIY is strong with you. I’ll probably be more apt to just buy some grommets as waiting for things to dry is not my forte, but great solution!