No need to wait till you get home
Here's the picy
Use the wooden blocks to set the manifold plate flat, set the angle of the dangle & correct tube spacing.
Once you have the jig made up, thread each tube through & mark a rough first cut ( Pencil or marker will be ideal )
When the first rough cut has been made, feed the tubes through and you should be able to mark a more exact cut line.
second cut made it will then be easy to fettle to a nice fush joint with a file
Finaly cut each runner to the desired length, this method is not too wastefull on matterial, a locost & easy diy method.
Light the Blue touch paper & weld it all up, jobs a good'un.
David, sorry I nicked your photo mate