The body of the fixture is coming along well:
First cut out the two end trapezoidal pieces, making them identical by stacking two pieces and cutting them at the same time. Then cut the front and back long pieces, making sure they are the same length. I set my skilsaw to cut at an angle, using one of the end pieces as an angle gage. That left the top and bottom edge at the right angle. These four pieces are then glued together - simple butt joints. (Which is when I discovered the front and back pieces were about 3/16" wider than they should be, so I have to trim them later.) Finally, cut the top piece using the same angle setting on the skill saw for the front and back edges to match the end piece angles. This is then glued on top of the assembled four pieces, using it to square up the "box". (I let the glue dry from the first glueing before glueing the top on.) After a short drying time, I used cut off strips of the MDF to reinforce all of the inside corners, which is when the photo was taken.