Add and Keep colors for outline to Laser Cut

[eocs]

Im creating a grafik that needs to be printed on plastic and then laser cut out. Idealy i would be able to add all the vectors and lines together into one shape and then set an outline to it. Testing has shown that using Add does not accomplish this as the colors also merge into one and the strokes disappear. 

I have all 3 affinity programs. Is there a difference if i just use publisher with the different personas for everything? Or should i be using Designer specifically?

How should this be accomplished?

Ive attached a file to show what i mean.

 

Thank you!

Edited February 5, 2021 by eocs

[Paul Mc]

I'm not sure if this is what you are trying to do but here goes...

Group the shapes together;

 

Duplicate the group;

Set the fill colour on the first group to transparent;

Select the two rectangles in the group and click Add;

 

Select the second group and set the line colour to transparent;

You end up with this:

 

This is visually equivalent to what you were asking for. Selecting just the top group would give you the vectors for the outline.

[Old Bruce]

I have a different method, select the innermost group to apply an Outside Aligned stroke, you can do that to the Group layer.