Here is some images including "Step by step" of my Groot mask.
It's made by E.V.A foam, hot glue and a pair of black eyewear lenses.
Quick tutorial:
1. Cut out a template in paper and then from a E.V.A foam board. (fits perfect on one board in diagonal)
2. Use Hot air gun shaping it around a head. (Ideally a cast of who will wear it). And hot gluing things together
3. Then comes the Detailing, detailin, detailing with cutters, sanders etc.
4. Try it on as often as possible. Last thing you want is to make it to thight....
5. Spray paint it. I used a leather brown
6. Shading get it by a inc wash to get the darkness in al the detailing.
7. Dry brush it with lighter brown and continue with darker details touch ups
8. Glue on moss and miniature grass.
9. Add in the sun glass lenses for eyes.
Thats it. About 10 hours of fun work :-)
Cheers