I am trying to make a cake with a similar pose to a standing big bird with his leg kicked out and his arms out that I have seen online.  It won't let me upload a picture.  I'm trying to figure out what internal structure is used to secure the arms.  Sorry I cant upload the pic. 

I think I have seen the one you mean. It would appear that the legs and arms are on an armature of some kind. I believe that one is one designed from Mike's Amazing Cakes. And he actually teaches a course on making it. But reviewing the pics, the base appears to be wood and the strong metal armature is attached to the board.

Someone on cake central posted on this here:https://www.cakecentral.com/gallery/i/2183331/big-bird-cake-from-mike-mccarey-class

And I see this note: here is a skeletal structure, but this is all real cake, covered in fondant and modeling chocolate. I see you asked the OP for this about it. But if someone paid and took a class to learn this, they might not be wanting to share that.  Mike still has sculpting courses on his site (although not this one). 

If I were to try it, I would build the strong metal armature on the board (It is obviously bolted into it. If within the armature there were a round platform near the leg and maybe another just above the arms, that would allow cake could be added in, frosted over and then use fondant and modeling chocolate to create the exterior and look.  Honestly, the design of this cake is more like a show stopper from Duff then one to actually be served and eaten. I would think it might be better to make a non-cake small figure with maybe armature and RCT to top a cake of use as part of a cake.  To make it a viable serving cake the figure would need to be quite large and need special cutting instructions due to the armature and build that supports the cake portions.

Thanks.  Yeah this one is about 2 feet tall.  Not doing big bird and probably going smaller.  I'm just trying to figure out the inside stuff I can't see. What hardware was used for the inside connection of the arms. Are they connected to the board or connected to the center support pipe. Is it a Y connection or DWV with elbows.   Thanks for your input. 

How you design the armature could be how heavy the materials you will use on it will be. And now I think we are at the zenith of my knowledge for this. I mean bendable wire could be viable if using say RKT. The outside materials, i.e. fondant/modeling chocolate could be a component to determine how strong that base needs.  You know, I did note seeing something from innovative sugaworks. I was looking at their delivery cool box but they have sugar structures prefabbed that might work for this application.  And you can adjust them to stand as you want.  You can see them here www. sugar works. com /collections/sugar-structures/products/sugar-structure-standing-two-legged?variant=35591640910  (take out the spaces). If you don't want theirs, it might provide an idea how to DYI it.

I used pvc pipe -- I went to a plumbing supply store and picked out all the elbow joints and different size pipe that I needed -- I use a thick mdf board, screwed on a flange I got at the same plumbing store -- build the pipe from the flange up -- there are a lot of different elbow joints, "t" shapes and cross shapes, etc.-- some elbows attach different size pipe -- bigger pipe for legs and body than arms or whatever -- I recommend getting the pvc pipe cutter and the plumber's glue--

there's a lot to engineer on cakes like this -- don't forget to support with dowel and boards where necessary for height like on any tier cake -- use waxed boards or plastic cake boards or foam core board threaded onto the piping -- I also drilled screws in to hold things together --

best ~