It's an improvised funnel with a tiny tip made out of a disposable plastic glass and a Bic ballpoint pen cap.
Step 1: What Do You Need ?
- a disposable plastic glass
- the cap of a Bic ballpoint pen (or anything similar)
- if required : some glue to fill potential leaks
Step 2: Build It ...
Make a hole at the bottom of the plastic glass.
Insert the cap.
Fill the leaks with glue if required and let it dry.
Step 3: Use It ...