You can look at my old set up here. It's a 55 gallon water drum with a door cut in the side. I used PVC pipes for ramps that ended in collection buckets. Although the system worked, I always felt the chances of the BFS larvae finding the ramp and using it were not as good as they could be. A broad ramp leading to a broad exit hole would be better, but you can't just insert a plywood ramp into your set up. First of all it will rot, and second of all, BSF can get through any crack and they will all end up lost on the other side of the ramp. Then I thought one day, why bother with a separate ramp? Why not tilt the whole container the 20 degrees I wanted and cut a long slit for an exit hole in the side?
Here is the design my husband and I came up with. The design was mine and the execution was his (of course.) The barrel is tilted at a 20 degree angle. The collection bucket is the beige container with the green top on the right. The drain goes to the jar with the red top on the left.
There is a slit cut inside at the high end of the barrel. The larvae will instinctively crawl up and fall out of the slit, into the collection bucket, when they are ready to pupate. The barrel was pretty full since I hadn't cleaned it out in a few years and it was very mucky since my old drain did not work too well. I have a lot of composting material to spread around now.
There is a wooden stop at the low end to keep the barrel from sliding off the support. My husband thought of this and this stop was really needed. You see I wanted to simply prop the barrel at an angle with cinder blocks and, no, that did not work, so don't try it. The barrel gets pretty heavy and just slides right off of cinder blocks. My husband stepped in at that point and built me the wooden frame. He's so handy!
There is a drain here as well. I pour the liquid in my compost tea maker.
At the other end we have a support for the collection bucket. We ended up making the slanted support for the bucket, because we could not figure out how to cut the bucket properly so that it would fit up against the barrel right. The geometry of a cube partially intersecting a cylinder at an angle was beyond us! So the collection bucket is tilted at the same angle as the cylinder, which makes it much easier to cut the sides so the bucket snugs up against the barrel. The wooden slice of a circle you see in the picture was what we used to draw the cutting line for the supports and the side of the collection bucket.
The lid of the collection bucket had to be cut too. We just measured from the exit slit to the end of the barrel, then fit it by trial, and no error thankfully.
Some of the larvae after a few days.