This does not need to be an expensive hobby – If you are resourceful. Lots of free, or close to free, stuff can be had/made for the layout.
I’ve made neat barrels from the moisture absorbing inserts that come with many over the counter or prescription pills. I just spray them red or green and paint the tops silver – done.
Sand bags and "bumper" tires:
Think out of the box - cereal for scenery??
The sand bags in the first pic below were made from Shredded Wheat and the bumper tires on the barge in the second pic are Cheerios
Need concrete barriers to protect tour buildings or roads?
From these clothes hanger size tags:
I made these barriers with a little grey primer spray paint:
Propane Tank Farm:
Buy your significant other quality roses – they come with tubes on each stem to hold water. I sprayed these with a grey primer, glued them together in two rows, added a propane company sign (cut out of the yellow pages) – instant propane tank farm.
Pink or blue Styrofoam scraps can make wonderful viaducts or retaining walls when worked with a hot Styrofoam cutting tool. I like the one called Tippi.
Landscape and Mountains:
Paper Mache, paper towels dipped in plaster draped over wadded up newspapers, even spray foam have been used to make mountains, etc. on Warrenville. Beaded white Styrofoam or old ceiling tiles makes a great basis for retaining walls when roughly broken and glued in rough layers with white glue.
I find that a 50-50 mix of sawdust and plaster provides a nice texture while still retaining the plaster's strength. It also dries quicker, something important for someone short on patience like me
I like to paint mountains, etc. with a grey latex paint and then dry brush with green, black and brown. Add groundcover, pieces of lichen etc.
Grass and Ground Cover:
Speaking of ground cover, even a small woodworking project will produce a couple gallon coffee cans of sawdust. Use some as is and use Rit dye to dye the rest green.
Don’t forget that dried used coffee grounds also make good dark brown ground cover.
Trees, Bushes and Foliage:
Fall is a super time to find weeds (goldenrod is great for this) to make trees. I pick the good ones, sometimes glue two together at the stems and shape with a scissor. I then spray them from both the bottom up and top down with green, red, yellow or brown spray paint, sometimes using a combination of these colors as a dusting over coat. I thicken and texture the stem “trunk” with hot glue and paint it a brownish-grey with latex paint.
In the months before Christmas pine trees can be found at the dollar store - a little work on them (dipping in diluted white glue and sprinkling fine ground cover on them) greatly helps their appearance. If you don't care for the "snow" that usually comes on these trees, spray them green first - that is what I do.
The trees shown in the gas storage tank tip below are additional examples of "free" trees
This mountainside is just thin, white, Styrofoam, salvaged from packaging, layered together with Elmer's white glue.
I then painted it with left over grey, green and brown latex paint and sprinkled sawdust, some dyed green with Rit Dye (just like in the 1950's), on it while the paint was still wet.
I then added small pieces of lichen and some week flowers sprayed green.
The figure on the right is a common Plasticville painter.
Flat car Load/Log "chains":
How do you hold loads to your flat cars? Burn the fuzz off of pipe cleaners and what’s left looks like chain/cable.
Like the stretch bands that Lionel uses? Pick up a pack of hair bands from your local chain drug or dollar store. Many in the package are white or silver and look exactly like those used by Lionel. Give the other colored bands to the kids.
Gas storage tanks:
Try the 1950's method of making these from tin cans, pieces of stiff wire and signs cut from advertisements! Piping in the case below was made from heavy wire. Plastic model sprues also works well.
We had a can of Cambell's soup for lunch today, when I peeled the label off the can to recycle it, I really liked the ribs on it.
Some spray primer, decals printed, a model part spew, a ladder made from balsa, a sign from an old map and a Plasticville painter and this is the result:
Fireplace Matchstick lumber
Free lumber for loads or construction can be had from used foot long Fireplace matchsticks.
Think out of the box!
This electric sub-station started its life as an automobile dash radio insert. The two black pieces on the left of the roof are pieces of packaging that held scale autos to their packaging. The circular object on the right front is a washer. The two grey conduit pipes in front are model spues. I don't even remember what the other pieces are from.
Not quite free, but only $1.25 at the "Dollar Store"
Check the Dollar store out periodically, especially just before Christmas. Often, I've found O and HO scale figures and scenery items there.
Most recently I found this dollhouse - looked to be O gauge:
With a little paint, I think it made a pretty good background "flat":
Several, painted differently, can make a whole block of background houses.
As a bonus, the furniture included will become part of a yard sale scene.
Derelict freight cars in your junk box?
Notice the double decker gondola in the pic below? I saw this prototype on a LIRR work train. To make mine, a junker gondola was cut in half lengthwise. Popsicle sticks were inserted on the inside, extending downwards about 1/2 inch. This makes it fit nicely inside a good gondola without affecting it. Add a load of your choice.
A free, unique, car.
Save those plastic model sprues!
I find that the sprues that hold plastic model pieces together can be useful and worth saving. I've used them for piping on buildings and tanks. Most recently as railings on a Lionel Arch Under bridge:
Washers, film containers, packaging, etc.
I try not to discard small items such as these - eventually I'll find a use for them.
As an example, I recently built a small emergency fire water tower from these "junk" pieces:
With some glue, spray paint and a flag decal that I printed, here is the final product:
Free Iconic Signs:
From a whipt cream can top and a cone made of painted paper to an iconic ice cream shop sign: