Where can I find the best custom challenge coins?

My organisation’s 5th anniversary is coming up in 45 days, and I want to give our top employees custom coins as a token of appreciation. I’m looking for coins with extra thickness, and I want the design printed on both sides. I also want to add a glow‑in‑the‑dark feature to the coins so that employees can remember their achievements even in the dark. Is there any maker who can produce custom challenge coins according to these specifications?