Lets start with the props, being a RPF member has been great to gather ideas and see what's possible with everyday items. Doing research here has been invaluable in putting this together.
The first thing I built were the 2 Pain Pill bottles seen in the game, using vitamin bottles similar in shape to those in the game, I added a replica graphic made by Peelz and printed a new label for them that resembles the one in the game. I then drilled a hole in the lid and used 2 key chain belt clip holders to attach them.
Next I tackled the Pipe Bomb seen in the game. I purchased some PVC plumbing pipe and caps, and attached them together with Plastic welder. I spayed them with some hammered silver spray paint and added a fuse at the top with some wire. I found a cool egg timer that had 4 red LEDs and had a speaker. Its not game accurate but once i stripped away the casing and attached it, it actually cycles through each light while beeping faster and faster. I attached that and the speaker and velcroed a 9V to power it. I also added a tire cap LED light so whenever its shaken the red LED flashes in it. Again not all 100% game accurate. but it adds a cool effect. I then also added a ring so it could be held by a key ring belt clip.
Next I tackled what I consider the money prop for any Left 4 Dead costume, the First Aid Kit. I was able to create 2 using 2 large red Molle packs I found online. I stripped off the straps on the front and glued on some zippers I got on ebay. The zippers are not functional but they gave them the right look. I used some strapping for the connecting black line and added some white fabric for where it says First Aid and where the + sign goes. Also on Ebay I found some embroidered + signs and glued them to the front, I then printed the FIRST AID text and glued that on as well. To make them wearable, I bought some strapping and some clips from walmart and made adjustable backpack straps to hold the kit in place. All in all they both came out really well, and can now be used as actual backpacks.
After doing some research I found that some folks had used VOSS water bottles to make pretty convincing Bile Bombs from the game. I decided to tackle that as well, and I bought 2 used 11.5 oz plastic VOSS water bottles on Ebay. I stripped off the label and painted the top portion of the bottle itself grey. I then glued cut toothpicks to the cap to make the ridges and painted that white. I then used some sheet metal to make the clip and painted the tip of that red. I then drilled a hole in the cap and added a cotter pin, and attached a key ring to it. The key ring again was added so this could hang off a key ring belt clip. After searching some images on google I found a nice replica bile bomb label, and an image for the safety seal. I added those as well and then researched a good recipe for green slime that would be shelf stable. I found a great one using 4oz of clear school glue, 1 cup of water, and 1/3 cup of Borax dissolved in water. You just mix that and add a few drops of yellow and green food coloring for some great viscus slime. I also added the ink from a highlighter marker to make it black light reactive. Unlike other materials, this can remain stable for several months if not years in a sealed container.
For Bill's costume, I found an old Army shirt and sewed on some patches, and for the beret I found a replica of the exact patch from the game and ironed that on.
For Rochelle's and Ellis's T-Shirts, I found comparable blank ones and used replica images from Google to make iron-ons for them. The Depeche Mode one was particularly challenging because it was Black, with White writing, with a green Underline but on a pink shirt. Even with a color inkjet transfer this would not have worked, so I make and Iron on with just the black element, and carefully cut out the lettering and the underline with a razor blade before ironing it on. I then used white and green fabric paint to color in the white lettering and the green underline.
The other props I collected for the costumes were a collection of Airsoft guns including a M14-A4 (with lights), a pair of M555AF Airsoft handguns (with Lights and laser sights), and Airsoft G6 handgun. I got a pre-made prop Machete and working Chainsaw, that were already blood splattered, and a prop Axe that I splattered with red paint myself. The rest of the costume elements gotten from Ebay or thrift stores include...
Rochelle's Brown Boots
Rochelle's Black studded belt
Rochelle's jeans
Nick's Blue Shirt
Nick's Holster
Nick's White Suit (Costume Suit)
Bill's Shirt
Bill's Pants
Bill's Military Boots
Ellis's Blue Mechanic Jumpsuit
Ellis's Trucker Hat (Bought the official one from the Valve store)
Zoey's Red Track Jacket
Zoey's Black and white converse style sneakers
Hopefully I captured all the elements that went into these, below are some close ups and progress shots on some of the props.
