Mark Cesarik. Trim by aliging the 1/4" line on your ruler with the pencil 1/4" line on the template and trim. The reason for the aligning with the 1/4" line is that, without it, you trim to the edge of the template, often take a little slither off accidentally and, by the end of the project, the template is smaller than when you started.
2. Cut a couple of WOF strips of background fabric 2 1/2" wide. I am using a selection of Oakshott shot cottons for the background and skinny strips. Sash the triangle and trim.
3. Take the 10" template, press onto the triangle at a wonky angle. Hold up to the light to check that the edges of the new triangle remain at least 1/2" away from the edges of the first triangle.
4. Trim, again aligning the 1/4" line on your ruler with the 1/4" line on the template.
5. Cut a couple of WOF strips 1" wide of the skinny strip fabric (here dark purple). Sash the triangle and trim.
6. Sash again using the background 2 1/2" WOF strips.
7. Press the 15" triangle template on at a wonky angle, again holding it up to the light to check that the edges of the new triangle are at least 1/2" away from the edges of the previous triangle.
8. Trim again aligning the 1/4" line on your ruler with the 1/4" line on the template.
9. Sash once more with the skinny strip 1" WOF strips and voila you have finished one of your copa cabana triangles.
What you do with them is up to you. I have yet made no specific plans for mine - I'm just going with the flow. If you do make any, let me know and add them to my Flickr group so I can see them. And any suggestions as to what to do with mine would be great please.