Sheet metal internal corner flanges

Greetings;

I've been enjoying the new sheet metal feature and am impressed by a lot of its workings.  Unfortunately, I think I may have exceeded the current capabilities of Onshape's new sheet metal tool.  I'm curious if any of you know something I haven't figured out yet.

I make relatively complicated parts out of ACM or Dibond sheets, which are 3mm thick composites with a 0.3mm aluminum layer sandwiched around a plastic core.  It cuts nicely on my CNC router and I can essentially score it where I want folds, then fold them by hand.  I used to use Solidworks to design for these by only modeling the outside 0.3mm layer and leaving a 3mm gap all around.  It was never very good at it an already Onshape has a leg up in the way you convert solids.

Here's my problem.  Nearly all my builds have some internal flanges which I use to rivet corners together.  The way I'd think I would use Onshape to make this gives me an error that it cannot make internal flanges.  Here is an example of one such assembly I'm working on:  https://cad.onshape.com/documents/58acb23415419f0f71099caa/w/e7ec785a478259d1ac449782/e/501d06d99e6189b96b13d6b9

I've made that public so you should be able to tinker with it if you feel the need.

What I'm trying to do is make this part have pentaradial symmetry.  That is, each of the edges of the pentagon should have a fold leading to a face, with that face leading to another face below it.  Each of those faces would have one flange to connect it to the face to the left.  Something like my desired outcome for each leg of the pentagon can be seen in the faces with flanges 1 & 2.  Only the very bottom of the part is left open. As seen highlighted below, I'm gunning for five sets of the highlighted faces.



I first tried to just add flanges after making most of the outer faces have the bends they need.  That gave me the error stated about internal flanges.

I then made the two faces to the left of flanges 1 & 2 have the bends now seen in those flanges.  I used move face to offset these by 3mm (which I don't think worked as I planned) and then used a remove extrude to make the flanges in the shapes now seen.  There are some problems, but I can work them out.  Where this fails me is I don't know how to make the rest of the legs of the pentagon like this.  At first I thought I'd use a revolve feature pattern, but I see that isn't working with sheet metal yet.

My last attempt has been dealing with the flanges labelled 3 and 4.  I found that by moving the face of the edge I'd like to make these flanges on, I could use the flange tool.  I cannot, however, get the flange to be parallel to the face it must mate with.  You'll see what I mean in the model.  I can't find a way to define it as parallel to a face so I figure that's not implemented.  When I attempt to define the degrees, it fails to generate with a nebulous answer as to why.  The one flange you can see is as far as I can bend it before it fails, and flange 4 just refuses to generate.

Any thoughts, or should I just work around this for now?