If I misunderstood your meaning of "cut down" I apologize; to be clear you can't make an edge plus by cutting an edge in half down the I beam lengthwise....that said
These had a few varieties, but the modern ones basically were identified by the inboard strobes. They either used corner modules with angled standoffs to make them front facing and flat or minimax / 700 series linear heads (except for corners). The ones made up of corner tubes were usually self contained and had blank sections for the power supply whereas the others were usually remote powered with isp series supplies.
Again sorry if I misunderstood, but to reiterate, you can't chop a standard edge to make an edge plus. These are not actually edge halves. The metal housing is specific and has grooves in the back (both internal and external) for mounting and they are about 30% the depth of an edge 9000. However, if you find an actual edge plus that is too long (much more common) these are not bad as far as cutdown is concerned, the issue is finding the metal end pieces, not so much attaching them.
A good source for a build is arrow bars that were built on this platform. I can't find it now but there was one for sale for $200 not too long ago. You can cut them down and make two 4 head bars so long as you source two additional metal ends.
Unlike the frames themselves, the endcap lenses actually can be (and were) made from cut down edge 9000 caps, so you can make those from standard edge end caps. You basically cut at the alley light, dividing the lens cap into thirds. I can measure one if you are making them.
Back to the internals; You can get standard edge internal components except for the angle pieces that make the corner tubes lie flat. If you cannot source these you can make them, I can provide pictures if need be. I find potted SL and EB potted style supplies fit more easily than open board ones, but the important part is figuring out where to house it.
I can grab some pics of one of mine if need be, some of it is a pretty tight fit.
When I am in search of edge parts such as internal mounts I usually hit up
jperrylighting.com
They have most internal components in stock for reasonable prices.
