Plain or fancy, any metal container with an open top can mold Jell-O. Decorate your kitchen walls with metal molds – they come in all shapes, sizes and patterns. Copper, aluminum and tin molds make interesting wall decor. Paint the outside for decorating and still mold gelatin in them. Speed up gelatin making by using a pre-chilled metal mold because metal transfers heat faster than glass or plastic, so the gelatin sets faster. Once the Jell-O is jelled, the tricky part is getting it out of the mold intact. There are several ways improve the odds of a perfect result.
Slip a thin knife blade between the gelatin and the mold to admit air and break the suction. Invert the plate over the mold, hold them firmly together with both hands and flip the lot. If necessary, give the package a sharp shake to loosen the Jell-O. This is the traditional method. The knife trick can be difficult to execute without scarring the gelatin, and the more ornate the mold, the greater the risk.
If the Jell-O won't come out of the mold, dip the bottom of the mold into the bowl of warm (not hot) water and submerge it up to the rim, but don't let any water get into the mold. Hold it there for about 15 seconds. Remove the mold from the water, add the plate and invert. The idea is to melt the gelatin touching the mold just a little so the whole thing can slide out. Refrigerate the gelatin immediately.
Spray the interior of the mold lightly with plain water before pouring in the gelatin mixture. When it has set, use wet fingers to pull the gelatin gently away from the sides. Wet the serving plate before placing it over the mold to make it easier to center the Jell-O on the plate. Wipe away any excess water before refrigerating.
Spray the inside of the mold with cooking spray or rub it with salad oil before adding the Jell-O. This will help it slide out easily, but may leave a film on the surface. If the gelatin contains fruit or vegetables, any film will be less noticeable.
Make an opaque gelatin by whipping it or adding cream cheese or cottage cheese and use mayonnaise to "grease the skids." It won't show.
Spray the mold with cooking spray and then line it with plastic wrap. If a clear gelatin jewel is desired, smooth out all the wrinkles in the plastic wrap before adding the Jell-O. For a "crackle" effect, push the wrap into lots of wrinkles. Turn the molded gelatin out onto the serving plate and peel off the plastic wrap.