Hope the jpg matcap and the possibility to add them will be removed forever since 2.8 viewport is color managed.
Otherwise it’s confusing for peeps not aware of color space stuff, plus it’s an aberation to color managed an already baked 8bit jpg (even linear jpg).
But I know it’s WIP an perhaps not the priority.
We definitely need something like this. Maybe a grid, vertical variation, or the ability rotate matcaps (maybe just in 90 degree increments) would be useful too?
An attempt at creating a hybrid of both horizontal and vertical reflection checking.
I used low frequency horizontal reflections and high frequency vertical reflections. Also tested to ensure quality. The high frequencies are a little blurry at sharp viewing angles. However, overall it works very well.
The chromatic aberration gives it a very nice look, btw. Well done!
This is it. That’s where it’s at! 
Yeah, this is a pretty good start – I hope something like this one gets included.
But man… those blurry edges. I almost want to say that Blender needs a dynamic, procedural, matcap system for things like this as the 512x512 resolution of a static image is reaching its limits here. That, or an integrated curvature analysis engine that will heat-map visualize the problems on your mesh 
I really like the procedural idea.
That’s how I designed it!
I work in Design in the Automotive industry and I have to say, they would be a killer features for sketch modelling. Easily making blender best in class for that!
I have to say that such reflection pattern should not be too hard to implement as a nodetree for eevee. And that would be perfectly smooth since it will be procedural.
better, I have done several tests with matcaps and patterns, and I have not uploaded them because they are not worth it. Apart from pixelated only the lines that cross the center or the rings for the edges provide useful information, the rest make water.
Proving HISEROD matcap, I see that it works much better than my tests.
A smooth clay matcap made by hand, good for sculpting soft shapes.
EXR:
http://www.mediafire.com/file/biaspdg5dms5myd/soft%20clay.exr
Just reproduced it in EEVEE, but using the vector transform node I get the mapping bug that you fixed not long ago.
Here’s another version of the Zebra shaders, as automotive modellers are used to. It’s pretty useless to demo such a shader on the waspbot, but it reveals modelling issues on the following hard surface model quite well:
Here are the two MatCaps:
Here is my first attempt hope its useful.
Can´t upload the Exr files… so here is the matcap in action.
You need to upload EXR file of your paint. You can use online file sharing websites like Mega or Dropbox or upload to your Google storage. Provide link to the file. EXR file is gonna act like source file so that developers at the end have freedom to export it in best suitable format.
