No argument from me on professionally installed rhino or line-x liners. However, depending on your budget you may look at UPOL Raptor Liner. The whole kit from
Amazon is only $100 and it comes with the spray gun you simply hook to your air compressor. You can control texture and thickness by the air pressure you spray it with. I was able to use it successfully, so it's pretty easy to do ( I have no painting experience). I used it on my truck topper and sprayed it with 80 PSI (high for fine texture) but most true bed liner applications should probably be sprayed at 40-60 PSI. There's ton's of youtube videos out there on how to apply. Here's a pic of my spraying in progress:
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