Since 3D printers are cheap to get today, it is worth printing out one or the other useful part yourself. The imagination knows no limits. Basically anything that you need can be printed. But you have to be careful about the strength and sun tolerance of the parts. Not all plastics are suitable for outdoor maritime applications.
There are a large number of printable templates on the Internet that you can use without having to construct anything yourself. A 3D printer can also be used to produce parts that can no longer be procured if something has broken.
On the 3D platform www.tingiverse.com you will find many useful print templates for a wide variety of applications. A small preselection for maritime applications is listed here: