Purchase a one-piece, fiberglass portable baptismal unit. These are fully finished fiberglass enclosures that are similar to the interior of a pre-molded hot tub. They are watertight and have steps for the baptismal candidates to enter and exit the pool.
Evaluate the weight of the baptismal pool when filled with water. One gallon of water weighs just over 8 pounds. The baptismal font will be incredibly heavy when filled, and the portable baptismal cabinet must be able to carry this weight.
Purchase six heavy duty, solid rubber ball bearing casters, which are designed to support the total weight of the cabinet. Purchase four swivel casters and two fixed casters for the bottom of the baptismal cabinet.
Draw and design a three-dimensional framed cabinet that will form the framework for the fiberglass baptismal. The bottom of the cabinet should be 3/4 inch exterior-grade plywood, supported by 2-by-8 dimensional lumber no further apart than 16 inches on center.
Draw and design the finish cabinet that will be built around the framework after the baptismal is installed. Make sure to draw into the plans access for the baptismal's drain plug, so the unit can be drained when stored for long periods of time.
Draw and design a matching lid that fits securely over the top of the cabinet, and latches into place. If the baptismal is left for any period while filled with water, a lid should be placed over the tank to prevent debris or little children from accidentally falling into the water.
Construct the frame for the baptismal font. Anchor all joints with 2-1/2 inch all-purpose screws for enhanced strength. Refer to any instructions that are included with the fiberglass tank to make sure and meet all manufacturer's requirements and suggestions.
Mount the fiberglass baptismal tank into the cabinet frame. The bottom-most surface of the tank should be evenly supported by the floor of the cabinet frame.
Cut and install the oak finish surfaces to the cabinet frame. Fasteners should not be placed through the fiberglass tank. The tank will move and flex when filled and drained, and any fasteners that are drilled through the tank will create stress points where the tank could fracture. The tank should "float" in the cabinet, held in place by silicone caulk around the lip, and built into the cabinet so as to allow expansion without significant movement or slipping.
Install the top edge of the baptismal cabinet so that it completely covers all unfinished edges of the fiberglass tank. The top finish boards should overlap the fiberglass tank edge so as to create a finished surface.
Stain and finish the oak cabinet once completed. Apply at least two coats of polyurethane finish to the cabinet to prevent the oak from water damage. Apply a bead of silicone caulk between the oak trim and the top lip of the baptismal tank. This seal will prevent water from spilling down into the cabinet, and it will prevent the cabinet or framing from water damage.
Install the casters on the bottom of the cabinet frame. Put the four swivel casters on the corners of the cabinet frame and two fixed casters at the center point of the frame. This configuration will create maximum maneuverability and improve the weight carrying characteristics of the finished baptismal cabinet.