I don't know if there's a tutorial for it, sorry! You'll need Pepakura Designer. NOT Pepakura viewer. you have to pay for designer, but i found a code online for it pretty easy >
. to convert a file, basically. you drag the .OBJ file into pepakura, some thing pops up asking you if you want to flip faces, just cancel it. Then you go to the second row of options from the top, and click the UNFOLD button. then your file gets turned into a mess of chunks and whatnot. now comes to part that takes super long. you have to go through that mess of chunks, and use the "Join / Disjoin faces" tool (you can find the Join/Disjoin" tool by right clicking on the 2d side of the screen) to separate all the faces from the model into the parts you would print out. It's also a good idea to rescale the model first, that way the pages are to scale. To do that, under 2D MENU, there's a "Change scale" option, then select "Scale factor" and under that, change the "Scale" just slowly raise it, then use the "Measure distance between two points" tool from the right click menu. that tool lets you well... measure the distance between two points, lol, using that tool, you can find out exactly how big your model will be, then just change the scale until you get it just right.
So splitting all the faces takes a long time, and you have to think ahead and find out what can stay attached, what can't. If you find a piece that you think is unnecessary, just drag it off the papers to the top left of the screen, that way it wont print those pieces. if you're using foam, make sure to go to the 2d menu and deselect "Show flaps" if you're using the fiberglass paper method, make sure to (when you're done) select the "Show edge ID" tool from the 2d menu, if you have that on all the time it will lag.
if you're confused about this then let me know! i dunno if i'm good at explaining these sorts of things. lol