To make 50 timers we needed to find a solid, light, clear, firm, case with a hole in the middle for the button. Sounds easy. We tried 3-d printing, using the small LED candle holders and buying coin holders but nothing has fit yet. So we are using epoxy--strong enough, clear, works but we cannot mass produce this. It takes us 3 separate pours to make one (each pour needs 48 hours to dry). We are still on the quest for a solid, clear, hollow case that feels good in a child's hand.