A pleasant little cockpit no one will see.

So, a red triplane it is.....
Richthofen's red 425 is not just a rabbit hole, it's a virtual mine field. Thankfully, others have spent considerable time and no small effort on this subject and now with the gathering of data on the www we have what I'm calling the "average truth". What follows are what most researchers generally agree on.
MvR's 425/17 was built especially for Richthofen by Anthony Fokker. Its construction was planned from the start to make it an improved triplane for the famous ace in its improved covering and finish. Some have suggested silk covering, more likely a finer, smoother weave of bleached linen. Clear dope applied to the upper surfaces then red, white squares for the eight marking positions, trace elements of colored dope found on surviving samples suggest the bottom finished in light blue. No colored dope on top other than red, no streaking.
So this is how 425/17 would have looked as it left the Fokker factory, red on top, blue on the bottom. Fok.DRI 425/17 in black over the red.
425/17 was test flown by Fokker test pilot Weidner on January 8, 1918.

Upon delivery, since all triplanes were light blue under, it is thought that MvR wanted a more positive identification from the ground for downed aircraft confirmation purposes and had the underside immediately painted over red.
In March, 425 was photographed at the Lechelle airfield with the crosses field modified in compliance with the latest Idflieg directive. It is not known if the entire aircraft was repainted or just the white squares around the crosses. So now it looks like this.

Between March and April 21, 1918, crosses again field modified with the bottom wing markings not quite finished as well as the other six positions. This is the final configuration of 425 on April 21.

I think it is a laugh riot I can not just go buy a single sheet of MvR markings in 1/48 scale for 425. Eduard includes it in one of their issues but thats it. So I found the sheet (#4837) from the "Ministry of Small Aircraft Production" and started hacking away.
The bottom crosses I may have another go at.

Since red covers so poorly, the white areas, the CDL, the light blue, all would have shown through the red. To that end, I primed the different parts white on top, grey below to simulate the light blue. This will show through on the finished build.

I experimented with different Vallejo reds. Straight 71.102 and a 50/50 mix of 71.102 and 71.003.

I'm leaning towards the 50/50 mixture. Three coats needed for correct coverage.

I can hear you snickering. Whadya think I just grab a can of red?......