I have a gazebo on my deck next to the sliding glass door to my house.  When it rains, I was annoyed by the constant drips of water that steamed down the gazebo roof between it and my house.  I fixed the issue by installing gutters.  These brackets mount securely without drilling holes or harming the gazebo in any way.   The top and bottom brackets screw together using M3 X 12mm self tapping screws sandwiching the 90 deg edge of the gazebo.  The gutter itself is made for 1 ¼" PVC that I cut in half with my table saw.  I used 5 brackets that get longer with each bracket to provide a slope to the gutter so water would drain.  My Gazebo is 12 feet long with a bracket every 3'.  I made a base mount and then one that was + 0.25, + 0.50", +0.75", and + 1.00".   I had to make several versions with different water passages to get them to work well.  Please see all the pictures to help understand this better.  My gazebo may not be built like yours.  I included Step and SolidWorks models so you can tweak my models if needed.   I printed mine out of ASA.  I included a PETG HF profile as well for those without an enclosed printer.  Enjoy!