Creating concrete tomb stones is not as difficult as it may sound and has many advantages over the traditional foam tomb stones.  First off, the realism is unmatched - You can have your guests touch and feel the cold stone.  Secondly, they offer the best form of theft protection - Weight.  Let's see someone snatch a 40 lb stone up and off it's rebar mounts and run off with it...  Thirdly, they are just about as simple to make as foam tomb stones once you have a base mold created.

Let's get started.  The first thing that is needed is a mold for casting your stone.  This can be as simple as a wood frame or as complex as a vacuum molded plastic casting.  For my purposes, 3 to 4 different width wooden molds works for me.

• 4' x 8' x 1/2" sheet of plywood
• 2" x 4" x 8' kiln-dried spruce stud (or similar - kiln-dried is highly recommended)
• 2 - 2' sections of 1/2" PVC pipe
• 2 - 2' lengths of 1/2" rebar
• 1lb box of 2" drywall or deck screws
• Philips head screwdriver (screw gun recommended)
• drill
• 1/8" drill bit
• 1" hole saw or spade drill bit
• table saw or band saw

• aluminum flashing
• sabre saw

• Acetic Silicone caulk (GE Silicone I works well)
• pure glycerin (CVS carries it)
• Acrylic paint (Small craft tubes from Michael's)

• non-drying molding clay
• base letters (recommended) - foam or sealed fridge magnet letters should work

For our first cast, you will need to determine the size of the stone you would like to produce.  Keep in mind that you will be working with a some-what fragile product so take this into consideration when deciding on the thickness of the stone.  My first stone was a simple square stone with no epitaph that was 18" wide, 24" tall and 2.5" thick.

Once you determine the size of your stone, you need to determine the shape.  If your stone is going to be square, there is not much additional work.  However, if you want your stone to have a curved top, you will need to design the top structure.  We will start off with a square top and I will discuss a more complex top later on.

Begin by cutting your plywood down to size.  The width should be 3" wider than the width of your final stone.  I recommend cutting the plywood the short way so that the resulting cut piece is <the width of your final stone + 3"> x 4'.  This will give us the abillity to keep all the components for this stone on a single sheet for easy pouring and reproducing in the future.

The next step is to cut your 2x4's to size.  First we need to cut them to length.  The final goal is to create an open-top, shallow box to pour our concrete into.  The easiest way to do this is take the width of your final stone and cut three (two for the mold and 1 additional section needed for aligning the inner rebar supports - the PVC pipe) sections to that width.  Now add 3" to the final height of your stone and cut two sections that size.  Save the remaining length of 2x4 for later.

Now we need to cut the 2x4 sections to the proper height.  It is very important in this step that your table saw or band saw be aligned properly.  If your blade is tilted, it could result in a stuck cast that will requre you to remove your mold walls to get the stone out.  So, first thing to do is refer to your user's manual for your saw and get everything properly aligned.

Once everything is properly aligned, cut the 2x4 sections to the proper thickness.  So, if you want your stone to be 3" thick, your sections would become 2x3's.  A quick word on dimmensional lumber:  When you buy a 2x4, you are buying a piece of wood that was rough-cut 2" thick by 4" wide while it was still wet.  As the cut wood dries and is finish-planed, it reaches a smaller acutal size than when it was rough-cut.  Therefore, the actual dimmensions of a 2"x4" are really 1.5"x3.5".  The moral of this little story:  measure to your actual size, don't try measuring what you want to cut off - If you need a thickness of 3", measure 3" of wood to keep, don't try and cut off 1" of wood expecting to get 3" left over.

To hold the concrete stone up and in the ground, we will hammer 3' rebar rods into the ground.  So that the rebar has someplace to go into our stones, we are going to embed PVC pipe channels about 1/3 of the way in from both edges of the stone.  To do this we need to create notches for the PVC pipe to stick out over the bottom of the mold.  If we simply drilled holes into the bottom mold wall, we would not be able to drop the stone out of the mold once it cured without removing either the top or bottom wall of the mold.  We also need to take into consideration that the PVC will want to float in the wet concrete.  To prevent this and keep the PVC as centered as possible, we will hold the PVC pipe down with rebar rods as the concrete cures.  This is the reason for the third section that was cut earlier.  To create these pockets in the mold wall, take one of the resized 2x4s that is the actual width of your final stone and draw a line down the measured center from end to end.  So if you resized your 2x4 to a 2x3, you would have a line down the side of your board 1.5" from each edge.  Now divide the length of the board by three and mark the center line at these measurements.  Trying to drill as straight as possible (a drill-press is helpful for this) drill 1" holes at these center marks.  Turn these holes into notches by cutting from the NON-CUT edge of the board.  The cut edge of our boards will be placed against the plywood when we assemble so that there aren't any undercuts (the edges of most 2x4s are rounded).  Now do the same to one of the other boards of the same width.  I know, a picture would be nice so I'll try and get one in place as soon as I can.

Time to assemble.  Begin by mounting the top edge of the mold.  Looking down at the plywood section so that it is positioned long dimmension vertical, allign the top piece of the mold frame 6" from the top and centered left-to-right.  The 6" of space will allow you to redesign the top of the stone in the future if you want to by creating modular top sections of the mold - More on that later.  With the cut section of the mold wall against the plywood, drill two 1/8" holes all the way through the mold wall and the plywood. Flip the plywood over and screw the mold wall to the plywood with the wood screws/drywal screws through the 1/8" holes.  Mount the sides of the mold in a similar fashion making sure there is just enough space for the bottom mold wall to fit in place.  Mount the bottom mold wall last.  Measure 5" from the bottom of the bottom mold wall and attach the other board with the notched out holes making sure the notches are lined up with the notches in the bottom mold wall.

Cut off 1.5 inches from one of the PVC pipes and cut this section in half so that you have two half sections of pipe.  Glue these pieces to the inside of the notches of the lower notched out board.  These will act as spacers to hold the rebar level in the PVC when you fill your mold and while it cures.  The PVC pipes will be placed inside the mold with 2 or more inces sticking out the bottom of the mold.  We will place rebar into the PVC pipes and in the lower notches to keep the pipes from floating while the cement is wet.