Hey guys - I'm going to add a few posts/pictures of my experience with these. See my last post for pics of the finished product.
One thing to note is that there is some fitting/adjustment to be expected, as not every truck/flare is going to be the same.
I started by installing and making some rough adjustments with a heat gun. For the most part, I concentrated my efforts on the fit to the body (it was a little loose), and the transition from flare to flare cap (the flare cap protruded beyond the flare). Heat the side closest to the tire to flex the flare cap and adjust the fit to the body. In general the process is: Heat the part, then hold in the position you want until it cools and holds it shape. It does take a bit of heat to get this done, but don't go overboard. When adjusting the transition from flare to flare cap, you will leave indents from your hands/fingers in the flare cap. These will need to be filled, but this is NBD - I just used some bondo.
First pic shows initial fitment.
Second pic is how I tackled filling the indents I made from using the heat gun to adjust the transition. Use a spreader/spatula to make the flare cap consistent with the profile of the flare. The bondo will also fill in the ridges from the 3D printing process.
Third pic is after a little sanding/priming.