Papercraft Necron Monolith. The pdf can be found here: [link]
or here: [link]
Instructions, as written by the author:
Page 1. Makes a simple box.
Page 2 does the same.
Page 3, same as the last two.
Page 4 is a mirror of page 3.
Page 5 builds a corner section. The flat white side glues to the front portal section (Page 1). The angled white side glues to one of the side sections.
Page 6 is a mirror of page 5 and goes on the opposite side of the portal, with the other side section glued to it as well.
Page 7 builds a back corner.
And page 8 builds the other back corner. Glue the back side wall between them.
Page 9 starts with the smaller parts. The six pieces at the bottom of the page are the bottom sections of the three spires on each side. There are two middle sections and two top sections of the spires on this page as well.
Page 10 has more side spire sections.
Page 11 has the four turrets with three guns each (formed as one box each). There are lots of little finicky blades to attach to the sides, but I figure most people won't bother with them. The large square part covers the gap in the top of the monolith and provides a base for the chrystal. There are four small supports that glue to this part as well. The back scoop is on this page, and requires the inside sections to be reverse layered so as to not show the white of the card stock used.
Be sure to use card stock instead of plain printer paper for this. Use a black brush pen or sharpie marker to color in any white edges showing. If you want your model to not get damaged, a clear spray varnish is also suggested.
I scaled it to 50%, have no idea how it relates to the size of the official plastic kit (feels about right, though). It is overall easy, the only tricky parts are top parts of the side “ribs”.
I used plain printer paper and it turned out fine. Didn’t bother with little parts for guns, they look better without them anyway. Also, be sure to glue in the top parts of side ribs last.
Monochrome printer, watercolor for portal, fiber-tip pens for everything else.