Firepit Concrete 3-Foot Diameter Molds – Boulder Random Rock Walttools-Stamps

Firepit Concrete Liner Stamp –  3′ Boulder Random Rock

• This Boulder Firepit Mold is designed for 2 of these liners to fit perfect inside a 3′ Sonotube.  We also have this Boulder style in a longer form (sold here) liner that 2 of them will fill a 4′ Sonotube! 
• Stacked Stone rubber form liner for making concrete firepits and seatwalls.
• Aggressively textured boulder style stones.
• Super simple to use to make a concrete firepit:  Just get a 3-foot Sonotube (from your local construction supply store), and get TWO of these liners and they will fit inside it.  To create the inner ring of the firepit, you can use something as simple as a garbage can filled with water (so it doesn’t move!)

Size Dimensions of Firepit Concrete Liner Stamp – Boulder Random Rock 

• Size: Each liner is around 14″ tall, and 57″ long.
• Liners have 1″ or more of relief (sticking out)
• Ends of the liners are staggered so they meet up with each other when using in a circle (again, 2 of these needed to make a 36″ circle!)

How to Use Firepit Concrete Liner Stamp – Boulder Random Rock

• Create the top coping cap / ledge in a number of ways:
• We have a specially made Rubber Edge Liner Form (sold here) just for this purpose!  It can be used in a form, but was designed to be screwed right to your firepit outer form (Sonotube, wood circle, etc.).  Some consideration should be taken to assure your securing it is adequate- a few screws probably won’t hold it securely once filled with concrete, so use a bunch or back it with some 2×4 braces if you aren’t sure!
• If you can pour the firepit base ring first, then you can come back and set up a Bendable Plastic Countertop Form (sold here) and one of the Rock Liners to go in it, and then pour the cap. 
• Another common way is shown in the picture below above shows an example where parts of the 36″ Sonotube were cut and spread lightly larger than the 36″ diameter and secured in place with screws.  Something like cutting 4″ sections of the Sonotube, and then cutting the ring open and sliding over each other, until you’ve built out a ‘ledge’ to your desired distance (@1″ – 2″ common).  Place some tape over these ring sections so it’s smooth and watertight.  Then cut another ring of Sonotube, 6″-7″ high, and place this around the outside and screw into place.  You can now set in a form liner for the edge, such as a 2″ or 3″ high rock or slate liner, and pour the concrete firepit and cap as one solid piece.   and a 2″ or 3″ Edge Form Liner can then be used to create the cap.
• When using a sonotube, occasionally the cardboard diameter will vary a few inches and the rubber liners may not fit perfectly- but this is fine because to use the cardboard tube, you typically will cut it open, either just one one side and then stretch the tube open, or cut the tube in half, and then clamshell around the liners.  In either case, once cut and liners inserted, use straps to keep the sonotube closed until after the concrete is done.