Worth mentioning straight away that these have been blatantly stolen from Bugbait_NZ's awesome scenery blog - link to his Infinity discussion here: http://infinitytheforums.com/forum/topic/15963-bugbaits-terrain-thread/
His original design featured 3 'notches' (and were about 7 cm longer than mine), but I've cut the design a bit shorter so that they will fit neatly into the CNC miniature scenery road tiles that I'm assembling, rather than hanging over both sides.The little cardboard template sits over a piece of foamcore and then cut with the notches on each side.
Once done, a very sharp scalpel is used to cut out a V-shaped portion on the 'inside' and allow the sides to fold up.
The end connectors are made by drilling a hole in the end of icecream sticks, cut into slices and then glued together with PVA. When gluing these together, I slipped the drill bit through the holes to make sure that they would line up when dry. End result is the set of blocks (5 sticks thick).
The blocks are glued into the foamcore, along with an extra stick on the top to give the middle a little extra rigidity (probably overkill, but whatever).
Very thick card (~2mm) is cut for the middle and end sections and is the piece that really holds the foamcore together - these get scored and scraped where they need to bend before being laid over the top of the barrier.
Little bit of extra detail added to one of the barriers - paperclips poked into the foam and cut out to simulate missile damage.
Couple of production line stages shown together... thin strips cut from manilla folder then draped over the joins (and used to cover the ends of the concrete sections). Thick card square wedged into the bottom of the notches.
Using a small hole punch to cut out circles from a cereal box, these get added on with PVA.
Last piece added is a tightly rolled & glued strip of paper to make a rod that would allow the barrier to be picked up by machinery.
Final step before painting is to paint all the concrete faces with watered down PVA and heavily shake with baking soda to give a cement texture.
6 barriers completed - sitting on one of the WIP Miniature Scenery road tiles and they fit neatly (about 5mm clearance) into the roadway that sits 3mm below the footpath level.