Plastic T-Hawk is designed. However it currently takes 7 sprues. Apparently the problem is that the big boy kit machine can only do 6 at a time. So the sprues need rehashing to try and cram it all in to make it economical. (I know, I know...) The other is that plastic Sisters are done. The timing of the new codex is an attempt to whittle down some apparently high stocks of current metal.