1. Copper Tray
The most traditional ones are made from copper. These trays are usually placed on a charcoal stove and the kueh bulus are painstalking made one by one. The cakes made from copper trays taste the best as the outside would be crisp and the inside will be moist and fluffy.
2. Electric Tray
These ones work like waffle makers. They give a nice dry texture on the cakes and each one is baked with the same consistency.
3. Aluminum Trays
These are like regular muffin trays with various shapes and sizes. The trays are usually placed in the oven and the cakes will turn out like regular baked cakes.
4. Modified Aluminum trays
I bought this for my MIL. According to the sales person at Phoon Huat, these modified ones can be used over a stove or in an oven. Hopefully my MIL will be successful in her attempts to make kueh bulu for my nephews.