This is the audio exerpt of iː spoken within a word. It may sound a little short or unclear, but that's exactly how it's in the real context. For more details, read the below explanation of pronunciation and listen example words that contain iː by pressing the word buttons.
1. Open your mouth for about 10%.
2. Relax your lips.
3. Push your tongue down, so that its tip touches the bottom teeth.
4. Push air from lungs while vibrating vocal cords.
5. Pronounce this sound noticeably longer than normal ones.