I've used most of the DIY bedliner products and I agree that the Duplicolor aerosol is the best of them. I've done lots with it but currently I have it on the rocker panels of my '01 Dodge Ram and it's held up quite well over two years and was applied over scuffed factory paint. I get it from O'Reillys, used to get it from WalMart but the ones around me switched to a similar PlastiKote brand which in my experience is complete junk.

Herculiner is good and looks incredible for about a week but then fades quickly to a chalky gray and seems to peel easier than some of the others. I use bedliner on lots of things around the place and until I come across something better i'm sticking with the Duplicolor. You can also roll on Duplicolor if you don't want to spray it, it comes in a jug with a special roller also from O'reilly's.

 

Charlie, I'm not to sure about how thick it is right now. I used a brush for the hard to get areas around the cross members and stuff and used the roller on the flat surfaces. It was enuff to get that rough edge so when your wrench or screw driver slips it will skin your knuckles lol. So far I haven't had any problems with it and when I paint the truck I want to go over it 1 more time just to be on the safe side and make sure shes all buttoned up...

 

The beauty of the SEM Metalock product is that it is actually 3 primers in one. Used straight from the can in a 4:1 ratio of primer to catlyst, it is a high build 2K DTM primer. Using half the maximum thinning ratio you will have a primer surfacer that works well for filling in scratches, etc in your filler. If mixed at full thinning ratio it now becomes a sealer, spray it on prior to spraying your basecoat and it will hold out bleeding from earlier paints and fillers. No need to sand the sealer coat before applying basecoat/colorcoat as long as you do it within the prescribed time frame.

SEM Metalock is available online for around $100 for the kit, 1 gal primer and 1 qt catalyst. I pay $85 here from my jobber. I don't use the Martin Senour line, not because I find it lacking but just because I have used DuPont, PPG, SEM, and HOK products for so long that I never saw a need to try something new.