Aha, thats done it, thanks. Knew it would be something simple!
For reference, I ended up with the code;
Code:
{ MERGEFIELD Metal1 }¶
{ IF { MERGEFIELD Metal2x } = "x" "¶
" }{ MERGEFIELD Metal2 }¶
{ IF { MERGEFIELD Metal3x } = "x" "¶
" }{ MERGEFIELD Metal3 }¶
and so on!
And it works perfectly