I use 3D Studio Max, which is not the best tool to do OPTs, but its all Ive got. A good CAD program and a good understanding of ACE_DXF you can build almost anything.
Vader's Tie Avenger/x1 has been around for quite some time, I used to use it in XvT. Not sure who did it, try DarkSaber or one of the other sites.
You can download my 1st ship at the link in my signature. I'm re-building the site right now, I just came online to get the URLs of a couple of sites.
"No no son, you gotta hit 'em in the head so they stay down, like this! *WHACK*
TK's OPT Factory