I've posted these pics and idea several times but for those who have'nt seen them.. I use these arboreal hides for all my morelia and its there prefered hide box by far for all my animals. the plastic tub sides in and out of the aluminium channel (thats been filed so there are no sharp edges) for easy removal and cleaning.
The black plastic tubs used, cost around $4 and are available at most of those $2 shops or Go Lo etc. The hide is snug enough to hold the weight of the snake and still able to be slide in and out for easy cleaning.
I used 1.5mm x 1.5mm x 1.6mm aluminium channel (available from Bunning’s) and drilled three small holes through each piece of channel the thickness of the screws. On the underside of the channel (that faces the cage floor) I drilled out the holes slightly wider so I could fit the screw head and screwdriver through to tighten the screws up. The main thing to watch for is to screw in the first piece of aluminium channel closest to the side of enclosure, and then fit the tub into the groove and slide on the second bit of channel. Squeeze it up close, but not too tight, as it needs to slide in and out for cleaning. Mark with a sharp tool through the screw holes, the position for drilling the holes for the screws of the second piece. If you have one, use one of those plastic drill guards to prevent drilling too deep into the roof, otherwise you can go straight through. The round hole in the tub was made with the largest size hole saw drill attachment, but you could just cut a square one out with a knife too.