Hi, I'm planning an enclosure as well! I recently got my beardie along with all his previous equipment just about 2 months ago but I think a bigger enclosure would make him even happier. He is about 8 years old just in case you were wondering.
Right now I'm still in the planning stages however I do have a 3d model that I made as a reference if you want to use it.
https://www.tinkercad.com/things/9AJJco39Ubz
https://www.tinkercad.com/things/0oJ5x3YqlHS
The dimensions are 1 mm=1 in adding up to about 52"Lx18"Dx27"H for the whole structure. It is specifically designed for a certain space so you might need to edit the design if you do use it. This is where it is supposed to fit along with Frank's (my beardie) current setup:
(he was a little grumpy because I had to rearrange his tank in order to fit his hide and his tree, he's much happier with it now)
Because the space in an open stairwell and a bit awkward do reach the left side of the tank, I designed it to have sliding doors and a slide out extension so Frank can have somewhere to walk right out of the enclosure without falling.
I'd love to hear how your diy viv goes. I probably won't be able to build my for a bit because I need to get the money and have my dad see if there are any other improvements that can be made. I'll let you know if anything pops up with it!