First off I want to give a big shout out to Chic Lasser's article on repairing dings and chips in the non skid decks of our Catalina boats.  You can find it in the Maintenance section on the site.  The information shared here is immense.  Chic's one lament was how expensive the mold pattern was to buy from certain providers.  I can't remember who posted this but somebody gave the suggestion to make your own mold from  2 part silicon from Tap Plastics.
I summoned up the courage and bought the ingredients to make the mold sheets and its was easy and a perfect mold of the deck pattern. I mean really easy!  Silicon will not stick to anything, pour and when set peel.
I purchased exact "light grey"  gel coat from Catalina parts dept.  $25.00 a pint plus shipping but the match is perfect.
I set out to do the repairs based on Lasser's article, but did this from memory.  I have to say I got incredible results.  The one thing I did not do, but will remember going forward, is to make a paste of the gel coat with Cabosil filler.  Its one of the most important parts of his instructions, and would have made the job 100% easier.  Here is a before fill photo which shows a strip of the silicon pattern.