Here are some converted Incinerator Grey Knights that I did a while back. I took the regular space marine flamers and reworked things a little.
It was not all that difficult to make that change. At the time, all you had was the solid pewter versions, so it was nice to have something different!
These also had more action to the poses.
I don't remember exactly what I did ( I could not find the WIP's for these two), but it was mostly green stuff and plastic rod.