A while ago I bought a box of Vertus Praetors, but never did anything with it, and realized that I had no desire to build an army of Custodes. At the same time, I wanted my Primaris army to have jetbikes instead of bikes, because I hate bikes.
So I decided to put together a jetbiker using the the Custodes parts with some Primaris mixed in. As it turned out, sacrificing a biker from the Indomitus kit was completely unneccessary as I wasn't able to make the lower body work with the Dawneagle jetbike. (I should've just taken a torso from one of the leftover intercessors I have lying around). Instead, I used the Custodes legs and arms, and swapped in the Primaris torso, head and backpack (which necessitated deleting the sissy bar). Since the Custodes model is slightly less chunky than the Primaris in Tacticus armor, I decided that the riders would wear Phobos armor with decorative trousers and half-chaps over it, and decorative leather glove over the left hand (the one that isn't holding the lance). I used the distinct Phobos shoulderpads and a standard Primaris helmet to complete the look.
While it's not a particularly brave conversion, I think it turned out OK. Here are the photos. What do you think?