Here is how to make your own cast concrete tombstones. These are easy, inexpensive, impressive and tough Halloween props, ready to spook in 24 hours.
Home improvement stores sell any number of different concrete mixes, and picking a suitable right one is the first step in the project. We recommend “resurfacing” concrete because doesn’t have any large rocks in it (in contrast to structural concrete). It mixes easily and forms a smooth surface. More importantly, when you carve into it, you won’t run into any of those rocks that aren’t there.
While it is tempting to get quick setting cements, they actually tend to set very quickly, and won’t leave much of a carving window. Regular concretes and cements are much more forgiving, allowing time to carve your inscription.
Besides concrete, you’ll also need a bucket and stick for mixing some of it, cardboard, tape, a heavy duty trashbag, a sandbox (or a reasonable facsimile thereof), and a cutting utensil. Rubber gloves are a good idea, too.
To create the basic tombstone shape, we’ll make a cement form out of cardboard lined with plastic that is supported– against the weight of the concrete –by sand from the outside. If you have a sandbox handy, you could start with that, and embed your cardboard form in the sand.
If you don’t have a sandbox, you can use a wide shallow bucket or a wooden box to support the sand around the form. For the curved top of the tombstone, cut the cardboard strips so the corrugation can be used to bend them into an arc. Tape the basic form shape together, and if you’re using a plastic bucket, tape the edges down to keep the sand from leaking under.
Add the sand around the edges of the form.
Split a heavy duty trash bag open to form a plastic sheet and line the form with the plastic. If you want a more decrepit look with cracks around the top of tombstone, leave the wrinkles in the plastic. If you’d rather have smooth top, tape the wrinkles down.
Follow the mixing instructions on your concrete. You’ll need a bucket and something to mix it with.
After thorough mixing, pour the concrete into your forms.
Stirring the concrete in the forms can help to smooth it out. You can also use a cement trowel or putty knife to smooth it out. Once it is mostly smooth (if it is in a bucket) you can lift the edge of the bucket and drop it down to help settle the concrete.
Let the concrete set up, checking on it every half hour or so. For a wetter mixture, you might have to wait a little longer to carve, but you may get more indistinct lettering that will look more weathered. Typical setting time is roughly 3 hours, and it should be hardened enough to remove from the mold after 24 hours.
When it is just hard enough, approaching the consistency of wet pottery clay, it is time to start the inscription. Just about any cutting tool will work–hobby knives are nice because the blade is disposable, but something like an old vegetable peeler/corer might be nice since you can make a curved indentation and lift out the excess material at the same time. If you have a “V” shaped carving tool, that could work well for chiseled letters, but the same effect can be emulated with a little patience and a hobby knife.
Once you’re done inscribing, let it sit overnight until set.
Once it has hardened, lift it out of the form with the plastic, and then peel the plastic off of the back. You can brush any loose concrete off with with a soft brush. If you want more even coloring, you can brush on thinned paint. You can even rub dirt (yes, dirt) onto the tombstones for a more aged look.
Install your tombstones in a strategic location.