Glaive weapons - scratchbuild

[Montuhotep]

Straightforward questions, probably not straightforward answers;

 

 I'm 'almost' scratchbuilding a Legion Glaive, using an old Shadowsword for the base model. I know the Glaive's carronade is in a turret but my skills don't stretch that far. So, the questions I have for you, Gents, are the following:

 

 What and how do I try building the Volkite Carronade with/from?

 

 What and how do I build the Quad Lascannon from, bearing in mind that I don't want to use 'blade sponsons at all and want the semi-circle mount the same as FW's model?

 

 A little help?