Need Silhouette Cameo help (probably easy!)

I think I know the answer, but I will play with it this afternoon to make sure I get it right.

Can you please tell me how you made the diagonal lines? With individual lines, or with thin rectanges? That can make a difference, too.

Try this:

Create a single triangle. I chose the regular polygon, which automatically gave me five sides, but with a slider bar inside. I used the slider to reduce the sides to 3.

Offset the triangle. When I do this, the second triangle is rounded by default. (Sometimes I don’t want it rounded, so I would change this to the sharp corner option in the Offset command.)

Offset the rounded rectangle. Delete the pointy corner triangle which is now at the center.

Select the two rounded triangles and then “Make compound path.”

Create two thin rectangles, and turn them diagonally to match the angle of the left side of your triangle. Move the thin rectangle into your triangle and shorten it to just fit within the inside and outside lines of the double triangle. Duplicate the tilted rectangle, move it to the right of the first one, and shorten as needed. Once it looks the way you want, select all the shapes, then choose weld. That will give you the following shape:

What works for me is to make each piece a compound path. I think that’s what it’s called. And then you can weld them. I hope that helps.