Well I did mine with a trip to home depot. Picked up some pipe caps, plastic T's, clear hose, and a hose fitting I used for a bulkhead/drain fitting.
Tooth pick was used to jam the caps on as the silicone sealant dried. Cut the T fittings push on hose fitting off the center and glued them in the pipe caps with 5200, keeping it flush with the inside of the cap so not to hold water.
Blazer Bay 2170, Yamaha F150, Minkota autopilot, Garman 178c