How to make a somewhat moveable and not very difficult grill with big possibilities for own taste.

Step 1: Build the Foundation

The first step is to build a foundation which will decide the size of your grill and most importantly your concrete top. This foundation is made of wood, treated to be able to be used outside as it is.

These wooden boards and beams are cut to appropriate lengths and assembled. The target is to get four stable legs and a box where an isolator can be placed and the fire be made. I'm using standard concrete blocks for this. Be careful when making the size of this as it will be more difficult to cut the concrete blocks than the wooden boards (as I noticed).

I've used screws to assemble and hadn't planned on the angled supports but realised they would be needed as it was a bit unstable before they were added. At the top of the four legs I screwed four bolts into the wood, leaving them sticking up a bit. These are meant to be moulded into the concrete top.

Step 2: Making the Mould for the Concrete Top

The concrete top is made from being cast in a mould. I purchased a wooden board made to make these moulds, which means it had a slick surface. After deciding what kind of grill I wanted and what size would fit the foundation I started making the mould.

I went for a square grid and a round hole to place a frying pan. The board was cut into a base sheet and several slivers. These were then placed as the outer rim by being screwed onto the big sheet. For the square a square was screwed together and to give the grid something to be placed onto two slivers were placed lying down, to give it a groove. This was also screwed onto the sheet. For the round hole an old paint can was used which was placed where the hole was supposed to be.

To prevent the concrete to seep between the boards silicone was added along each crack.

Step 3: Making the Concrete Top

Before you start mixing the concrete you have to make certain the mould is sealed and sound. You should also cut a fitting concrete reinforcement from a steel grid. Make sure it covers all the parts of the mould and that you can put it into placed when you have filled half the mould with concrete, and thus cannot move anything around.
I used a bolt cutter and cut away the parts that would be in the way.

As my plan was to cast the wooden construction and the bolts on top into the concrete top I nailed two boards to be able to put it into place as the concrete hardens around it.

To cast in concrete you should preferably have a mixing tool. Unfortunately I hadn't. However you can mix with a shovel, though you have to mix for quite a while and it gets heavy going after a bit. When you have mixed everything to satisfaction you can start pouring/shoveling it into the mould. Be careful when around the paint bucket as it could move if it is not fastened.

When half the concrete is in place put the concrete reinforcement grid in place. Then pour the rest of the concrete on.
When everything looks good, place the wooden build as planned and make sure the bolts are sticking down into the concrete.

Hammer the sides as you fill the mould and afterwards to rid it of air bubbles. As it starts to harden, water it a few times each day. I decided that my slate was finished after about 50 hours.

Step 4: Assembley

To extract the concrete top from the mould I had to unscrew the sides. However it turned out really good, there were some air bubbles I hadn't gotten rid of but that won't matter on an outdoor slate.

I realised when I was about to do this that the wooden stand hadn't really moulded together with the concrete top. The bolts had pressed down into the concrete but that hadn't filled up around it. This made the top remove able and still had some bolts which fitted into grooves on the slate which would prevent it from sliding off.

I now placed the concrete blocks in the wooden stand to make a safe box where the fire would be placed. I hadn't really measured accurately enough and they wouldn't fit as I planned. This requires some cutting of the blocks which I haven't had the opportunity for. However the picture shows a similar placement, the difference that they don't reach up to the top slate and thus do not cover the wooden stand. This will be rectified with some cutting..

The grill grid is cut with a metal cutter from a bigger one I found. And a frying plate is also added. In the open hollow a baking tray will be placed. This will be where the fire is. To make it easier to clean and move around depending on if you want fire under the grid, the pan or both..