I try to be pragmatic in building props. Props are a representation of a real object. And it will be used for only one season and then discarded. It needs to be constructed well so it functions properly and safely for the show and can tolerate rough handling. You can build props from any material but cost is always a large consideration so I have put together a short list of material I have found to be cost efficient and durable. These are my go-to materials. When I am in the design phase these are the materials I have in mind using.
Material costs can vary wildly. After your design is set, assign someone on your prop team to call around locally and check the internet for pricing. Your band probably has a 501 C3 non profit designation so don't exclude commercial material suppliers. Most of these places will accept a 501C3 in setting up an account. Use it! But I have found the big Home Improvement stores are generally cheaper on most things except hardware. A hardware distributor can usually beat the home improvement store in price for nuts, screws and bolts.
While we are on the topic of hardware, choose the right size hardware for the job. 90 % of the time I am using either 1/4" or 5/16" fasteners. I always use plastic lock nuts to avoid using lock washers. I use a lot of drywall screws, crown staples and finish nails in wood construction. 3/16" pop rivets are also a very useful and inexpensive fastener.
A welder can have a high initial outlay in $ but can quickly pay for itself because you will not have to buy expensive steel connectors. Buy welding supplies (wire and gas) from welding suppliers and not big box chain stores.
EMT electrical conduit. - My favorite! Strong and durable for props. Available at you local home improvement store. Cut it using a with a 14" metal cut-off saw or a use a 4 1/2" high speed grinder with a cutoff wheel. If you need to form a large radius you will need a tubing roller which can be bought at Harbor Freight for $169. For single tight radius bends, a hand bender can be bought at the home improvement center. The harbor freight bender comes with mandrel rollers for 3/4", 1 1/4" and 2" tube sizes. The 3/4" rollers will also roll 1/2" conduit. EMT is the only tubing I have found that the 1/2" tube fits nicely into the 3/4" tube which fits nicely into the 1" and so on. This is a really handy and useful! The towers you see in the background image were built as 3 - 10' sections with 1" tubing at the bottom, 3/4" in the center and 1/2" tube at the top. In the picture they look the same size!
Attach the EMT pieces together by using EMT fittings, welding or flattening the pipe and fasten using 3/16 or 1/4" pop rivets. Also, just this year I found that PVC barbed irrigation fittings work well connect EMT pieces together. These barb plastic fittings are found where flexible PVC irrigation pipe is found. Drive them in the EMT with a hammer and secure them in place with a 3/16 rivet. Great for panel frames and other non-structural pieces.
PVC pipe- Not my favorite material but useful in certain circumstances. The pipe itself is ok abet floppy, it's the fittings that are the problem. They are weak and cannot take much stress unless you go to the larger sizes. Plus you are limited as what you can do with it. But if you look at the props I have built for the winterguard show with the large 5' x 10' panels, the entire frame is made from PVC pipe and fittings. I did have problems with the pipe and fittings breaking and constantly had to repair them from being stepped on and slammed into door frames. But then again there were 22 props!
Lumber and plywood- Easy to work with but heavy. Curved structures are difficult but not impossible. I primarily use it to build the base of props. But I recognize that many of you have experience with carpentry which is me! But you need to change your approach when building props with wood. Don't think deck construction and think more along the lines of cabinet carpentry. Light and strong where glue is the primary fastener augmented with bolts and screws at the high stress points. This technique relies on plywood carrying the majority of the load with light wood strips at stress points. Old school kitchen base cabinet construction provides a great example of what I am talking about here. Glue everywhere wood meets wood fastening with crown staples and pin nails. The staples and pins nails only hold it together until the glue dries. Add screws and bolts where there are high stress points which is usually where wheels are attached. Avoid using pressure treated lumber. It is heavy and does not hold paint well.
Nut and Bolts- Avoid the Home Improvement and Hardware stores for Nuts and bolts!!! Find a hardware distributor and buy the hardware from them at a significant savings! For example 2ea 1/4' x 20 lock nuts from Home Depot will cost you 99 cents. You can get a box of 100 from the hardware distributor for $2.50! It is the same for washers and bolts! As much as possible I use nylon lock nuts. It avoids having to use lock ring washers and I like knowing the nuts absolutely will not loosen and create a problem.
Fabrics - A useful reference on different in fabrics is HERE.
For general use Preen brand ground cover fabric sold at Sams Club comes in a 4 foot wide by 225 foot roll for $30 is a great deal. It is thick, black, and does block most light. You can use it to make skirts around prop bases and to make back drops. You can sew it together to make panels as wide and large as needed! I used it in the Vegas Show behind the rope light so the props would not be back lit. But the most important thing about this fabric is it is quiet. Unlike plastic it does not rattle in the breeze! And being a flat black it does not show creases and wrinkles like plastic does.
Opaque ground cover fabrics are sold everywhere that you can put lighting effects behind and it will hide the lighting effects until you turn them on. Light passes right through it. Check the fabric by placing your hand behind the fabric and make sure you can clearly see your hand in normal lighting.
Sharkstooth Scrim- This is open weave fabric that when backlit disappears. Used in theater productions to make objects appear and disappear. Information here and here.
Adhesives - Wood- Good old Titebond wood glue is a great choice.
Fabrics- To bond fabrics and vinyl sheet to metal and wood there are a lot of choices in adhesives but I have found that only 3M's Spray-On High Strength 90 performs well in all conditions. Any other contact adhesive can let go with props sitting in the heat of a box truck. A good quality duct tape works well holding all vinyl fabrics to metal and PVC frames but not wood. Duct tape will not hold cloth fabrics well. Use contact adhesive with cloth.
PVC - You can use PVC adhesive but I have found that since the fittings tend to break I now attach them to the pipe with pop rivets. That way if they break you can drill out the rivets and replace the fitting without having to rebuild the entire section.
Panel Materials - Coroplast Sheet is corrugated plastic (as opposed to cardboard) and has many general uses and is very light weight. Information here. Sintra is another plastic sheet material that is more moldable and shapeable than coroplast. Info here.
Mirror Material- Rosco Shrink Mirror is a plastic laminate you stretch over a frame and is available in several sizes. Installation instructions are here.
What materials have you found that work well???
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