Pepakura is a paper modeling/unfolding program from Tamasoft. They are totally legit. The free programs work great.
Pepakura Designer
The program can read various 3D image files and help you "unfold" them into flat 2D representations, much like a puzzle to be
cut out and built.
LOTS of folks out ther have the paid designer program, and develop "unfolded" versions of different designs into PDO files.
A google search on your favorite subject, followed by "pepakura" or "PDO" will probably give you a GREAT starting point.
"So you have the Pepakura reader/designer and some PDO files, what next?"
Look at the file in the designer and play with some settings to get to know it. When you are ready, use the Pep software to print your design onto cardstock.
Some folks use regular paper, but cardstock will be easier to work with. You can then cut out your design and match the edges of your cutouts to other parts in the design.
You can turn edge numbering on and off in the program and there are a few things to know that will help. The design features solid lines, dashes and dot-dashes. The solid lines are for cutting. The dashed and dot-dash lines are for folding. Looking down on your design a "------" or
regularly spaced dash line will be folded like a mountain peak. or at least will follow a curve/bend toward the ceiling. The
dot-dash lines "._._._" will be the valley folds and fold like a "V" or a bowl shape.
I like to use flat, thin (they have thick foam ones, you dont want those)
photograph mounting strips found itn he scrap-booking section of a craft store to match the flaps to their corresponding "face" on various peices.
Anything that will help you cut paper and stick paper to itself is welcome here.
After you finish your paper model, you then decide what to do with it. That particular part of the discussion is a longer post yet, but this should suffice to get you started.