If all your laminations are wood, URAC 185 will work without a heat box. If using dissimilar materials then use Smooth-On. A temporary hot box, big enough to hold a riser and clamps, can be made with cardboard and masking tape, insulated with an old blanket or sleeping bag, and heated with a hair dryer. Other then the masking tape all the needed materials can be found around the house or can be obtained or for free. Here is what worked for me:
Build or obtain a cardboard box just big enough to fit over your clamped up riser and clamps. Make two openings in the cardboard box, one near the bottom big enough for the hair dryer nozzle to fit all the way in. Make sure the dryer is all the way in and tape or tie it into place (I used wire ties) to keep it from vibrating out. Cut another hole about the same size, five or six inches from the bottom near the corner on the opposite side, this hole allows the air to circulate and escape. Cover the box with the blanket or sleeping bag making sure the hair dryer and ventilation hole is not covered. Turn you hair dryer on high and leave it for six- eight hours. Like most things, do a dry run before gluing up your riser to make sure everything fits and works properly. One caution, do this on a non-flammable surface, I used the concrete floor in my garage.