A Space Marine's power armor is sealed against vacuum, but the air inside can decompress explosively if the seals are compromised. They can break when put through the extreme forces involved in combat – like a bolter shell to the chest. Though a Space Marine can go without air for some time (courtesy of his various genetically altered implants), explosive decompression will still inflict considerable trauma if he accidentally holds his breath.

How It Was Done
Assemble a normal Space Marine model, but substitute an Assault Marine's legs and a Space Marine Biker's left arm. Arch the back to suggest internal bursting and other trauma. Position the arms to look like they are flailing in reaction to the decompression.

Cut out a small piece of plasticard to fit the top of a 25-mm round base. Use a pin vise and a woodcarving tool with a V-gouge to create the deck plating. Drill a hole in the Space Marine's foot and a corresponding hole in the base. Use superglue to glue a paper clip piece to hold the model in space as if it had just floated off the deck of a battlecruiser.

Some planets hold life forms that are so persistent and pervasive that even Space Marine Chapters are ill-prepared for combat in these places. What if a planet's flora, spurred by some type of celestial phenomenon, grew at a highly accelerated rate? A world covered by fungi, molds, and bacterial slimes would prove an interesting battlefield. Especially when they are growing so fast that to stand still is to become a petri dish.

How It Was Done
Assemble the Space Marine in a hunched position. Cut off one or both of the exhaust ports. Leave off one shoulder pad. Spread large blobs of green stuff over portions of the model, especially the back of the Space Marine and any gaps that resulted from assembling the model in a stooped posture.

Use a sculpting knife and pin to add detail to the putty (make sure to keep your tools wet to prevent the putty from sticking to the tool). Roll the green stuff into small balls of varying size and apply these to the putty that already covers the Space Marine. Roll more small putty balls and then flatten them on a thin piece of paper (the blobs should be slightly rounded since they're going to be mushroom caps). Allow these to set and then cut them free from the paper to form mushroom caps. Use a thin paperclip for the mushroom stalks.

Use a pin vise to drill holes into the Space Marine and then insert the paperclip stalks into place with a drop of superglue. Put a drop of superglue on the tip of the exposed paperclip for the mushroom cap.

As slight twist on the fungi-covered Space Marine shown above, we included this Space Marine that has become encrusted by annoying, rapidly forming crystalline growths. This conversion was a really simple one to complete as all you really need are special pieces of plastic rod and your trusty X-Acto knife.

How It Was Done
Cut each side of a hexagonal plastic rod (Plastruct brand – available at HobbyTown USA) at a 45-degree angle. These cuts form the point of your crystal. Next, cut the plastic rod to a desired length.

Some planetary atmospheres are so brutal and unforgiving that even a Space Marine's protective armor can't stand up to the harsh elements of such an environment. Worlds with acid-vapor clouds are known even in the Solar System – the galaxy must be littered with similar planets. These clouds and other harsh chemicals could eventually pit and dissolve even power armor blessed with the strongest holy unguents applied by the Chapter's Techpriests.

This conversion for caustic environments could also work for Tyranid bio-acid, as these xenos sometimes have a powerful corrosive agent instead of normal blood.