Have you tried collaging?
It is one of the best & engaging ways to introduce letter formation. We did collaging a few years back when we were introducing the hijaiyyah letters to young children. In this activity:
1) we printed out the outline of the letter we were introducing
2) children paste the material provided (e.g. buttons, stickers, bits of foam paper, bread tags etc.) onto their letter outline & leave it to dry
4) children move their finger on the collaged letter to learn its formation
5) children may say the letter name as they move their finger, too!
Click here to download hijaiyyah letter (alif to ya) outline for your personal use. May it be beneficial.