Gather a small bottle or tube with a tight cap
Make a tiny hole in the cap
Insert a short piece of plastic or glass tubing through the hole
Seal around the tubing with waterproof adhesive
Attach a rubber bulb or squeeze top to the bottle if needed
Fill the bottle with liquid
Close the cap securely
Test by squeezing or tilting to release drops
Adjust the hole size if the drops are too fast or too slow