Lips
Mouth mid-open and neutral for "eh"; hold roughly the same shape as the r takes over. The diagram shows the mid-open start.
The American "square" vowel: a short "eh" gliding into the r colour. It ends on a real r, unlike the British version that fades to "uh".
Example words: square, hair, there, care, wear

Mouth mid-open and neutral for "eh"; hold roughly the same shape as the r takes over. The diagram shows the mid-open start.
Start mid-front, as for "eh". Then curl the tip up and back, or bunch the mid-tongue, into the r. The tip never touches the roof of the mouth.
Medium. A quick, clear "eh", then let the r colour carry the rest of the sound.
Say "there" and stretch the ending. You should hear "eh" flowing into a steady r you can hold for a second or two. If it dies into "uh", or you feel a tap, adjust and repeat.
Dropping the r so "hair" ends on a weak "uh" (that is the British version), or tapping and trilling the tongue against the roof.
🔊 plays the app's native voice. 🎤 records you so you can play it back next to it. Your recording stays in your browser.