I was wondering, I have daily drive I just got done rebuilding and it has a nice hole in the front bumper where the latch is.. (previous owner couldn't get the hood open so they decided to cut a nice hole...) Would window weld work to fill the hole and then sand? I'm not looking for professional results and don't really want to spend much for the repair, so I was wondering what anyone had used to repair the urethane bumpers for a cheap remedy besides buying the plastic welders etc.

There are urethane bupmer repair kits that you can buy for ~$15 IIRC. I've used them in the past with decent results

If your going to do it half ass I would leave it the way it is. Not trying to be rude, but the bumper covers are fairly inexpensive on craigslist, ebay, or even rockauto.com. I wouldn't suggest using a material such as the one you are asking about. They make the plastic welders for a reason. If your going to do it, do it right the first time. But if you think you have found a way to get it done, then do it your way. That's the joy of owning your own car, you can do it how you want.