You can buy a temperature regulator for lizards, it has a probe, temperature selector and a plug socket on it...you can put heatmats in the drying area and once it gets to the desired temperature (around 70-80F, 21-26C, mid/lower range is better) it switches off. Im from Ireland so we have issues with cold, this method makes sure we can always dry buds at the proper temperature. For the box design, you literally need a space you can hang them in with a small fan and plenty of air circulation. If your doing it in a sealed box (wardrobe, cupboard, etc) you should "burp" the box several times a day or put a $h1tl0@d of silica gel packets in there to control humidity. Then just enjoy your smoke!