Very simple and economic for your husband's sake.
I use plain old aluminum foil like for the kitchen and tape it to the outside walls of the cage (the ones you don't intend on looking through) then I tape thin pieces of polystyrene board over that. For the lid wrap 1/3 to 1/2 of the end where the lamp doesn't sit with foil. It really doesn't restrict the air flow in a detrimental way. I'm away most of the time during the day so for one of the cages I also have a removable panel of polystyrene wrapped in foil that I put on the frong viewing pane when I'm out and not wanting to watch the snakes. Now none of this is all that aethetically pleasing but it works. If you have a nice background on the cage already put the foil over it on the back outer side since the point is to reflect heat back even if it isn't reflecting light back. Space blankets chopped to fit also do the trick. Give it a try and tell me how it works
I can get a decent temp rise on a 40 breeder using this method. Be careful with Pumpkin Jack though since his cage is smaller, you will want to adjust the foil on the lid as needed.
, and whether or not it's ok to obstruct the airflow through the top screen. We have Spectre in a 30 long (a palace my daughter insisted that he had to have...she saved her own money too!), and Pumpkin Jack's only in a 10 gallon at the moment.
