The basic construction is the same for anything. You just vary the stitches you use from slip stitch to single crochet to trebles depending on how big the eyes are and your yarn in relation to them. For big eyes and thin yarn use taller stitches. Depending on how prominent you want the eyelids to look you can also add a third round. I recommend decreasing another stitch or two if you add another round to keep the eyelids snug against the eyes.
Eyelids for frog
dc =double crochet
trbl = treble crochet
dc/trbl-inc = dc or trbl as noted twice into the same stitch to increase one stitch.
dc x2 just means dc in the next two stitches
Pull magic loop closed after the first round but not completely, you want to leave room for the shank of the eye.
Repeat instructions inside the ( ) as many times as noted
Start with a Magic loop
Round 1. dc in loop 14 times, slip stitch to join into round.
Round 2. ch 3, (trbl, trbl-inc) three times, dc x2, dc-inc, dc x2, dc-inc, dc x2 slip stitch to join.
Cut yarn leaving a long tail, thread through eyelid and when you attach the eyes take it through the head of the frog and sew the thread down. You don’t need to sew the eyelid to the head the washer and eye will hold it on pretty tightly, but you can if you want.
And that’s it. This will give you a slightly more prominent eyelid on one side, when you attach the eyes put that bit at the top of the eye.