I longboard, and I find it an amazing experience. But like many great hobbies it is rather expensive. So I took it upon myself to build my own longboard. I'm very happy with my board and so I'd like to share how I did it.

First of Some notes.

-Cost to build deck-$30 + the use of equipment
-Things you will need .....Plywood,
                                        Strong wood glue
                                        Sawzall/Band-saw
                                        Sandpaper
                                        a frame, if you plan on giving you board concave or flex. (there are many ways, I used lumber.)
                                        Power-drill
                                        Patience

Step 1: Gathering Material

Buy enough 1/8 inch plywood of the type you choose to make a 50'X12' piece of 4-5 layers.
Also Buy enough 2X4 to build your frame. For me that meant buying two 7 foot pieces.

If you are making your board out of wood, the best and cheapest way is to use plywood.
It will be stronger, more flexy safe, and will shape easier if you plan on gluing more thinner sheets together than fewer thicker sheets. I used Three 1/4 inch pieces, leaving me with a fairly stiff board.

1/8 inch would be ideal using 3,4, or 5 depending on your weight and the flex you want: for most probably 4, making a half inch board.

I recommend using cherry-wood, maple, or birch, or any combination of the three

Step 2: Building Your Frame

As you can see in the pictures I built my frame to give a negative camber (which is the way the board would bent if you were to look at it horizontally as it roll free on the ground) which was to compensate for my weight when the board flexed. So the board naturally has a hump till i step on it, and due to the flex it bends, just enough to be horizontal with the ground under my weight.
I measured my two by fours and cut them into four 40' lengths before making a large half circle template out of cardboard and traced it from the middle of the board to both sides at to make the hump symmetrical. I then made one continuous cut with the band-saw (you could use a sawzall) on that line creating two sides: the side with the hump, and that which the hump fits into. This is going to be the camber of my board. you can do it with any shape, just dont make it too drastic because it will be harder on you. I recommend screwing these to another board to make all the elements of both sides (the hump and that which holds the hump) more manageable. Because essentially you are putting glue on your boards putting them together and clamping them between these two sides to glue the board into the shape you want.

I also highly recommend using templates for whatever frame design you want to build. Draw on it half your camber design, cut it out, and then trace it onto the board from the middle to both sides as to make everything the exact same and symmetrical.

Step 3: Gluing Your Deck

First lay out a large area with news paper and wear old clothes and gloves because there will be a lot of wood glue dripping.

Using your 50'X12' plywood boards, apply a healthy, rather generous amount of wood glue (tight-bond works fine, or even gorilla glue if you please, just any recommended generic wood glue) to both sides of the wood you are putting together and put them flush with each other. Do this with all your pieces before you put the whole thing into the frame. No need to work very fast, be patient, (you are going to get glue on your hands, or wear gloves) just don't leave it and bake a cake. It even makes it easier to clamp on the ends of the boards to make sure they are flush, just don't put it on two tight. Also put a little rip of paper between the clamp and the deck so your board doesn't glue to the clamp.

Place the entire thing onto one layer of your frame (the more stable one) and place the other side of your frame on top. Its also not a bad idea to do the paper trick with the frame so your board doesnt glue to the frame. Put a layer of paper down on the frame and on top of the deck once you have laid it down

With the ready clamps slowly from all angles clamp down the boards between the two sides of the frames, tightening gradually all the clamps, This is much easier done with a friend.

When you are done and all the clamps are tightened as much as you can, take a rag and wipe off as much of the excess glue as you can. If you dont have the paper there, you dont want your board becoming stuck to your frame.

Let sit for at least 24 hours!

Step 4: Designing Your Board

After contemplating the layout of your board take a piece of cardboard and a str8 edge on one side. Then trace only half of your board design lengthwise onto the cardboard.

Next cut out this drawing, effectively making a template for half your board.

After waiting 24 hours you can unclamp your monstrosity of clamps and fine the center of what would be the front and back of the board.
Draw a line between the two points so you have a dissected board.

Place your cutout onto the board and trace your outline onto one half.
Flit it over and do the other half, making a symmetrical outline of your board to be.

Take your sawzall or band-saw and cut out your board.

Go Slow
Be patient. Cut well next to the line as to give yourself some room for error.

Step 5: Finishing: Drilling and Sealing

Now you have ha sweet looking deck =)

Take your sand paper and sand the edges and all the glue stains to make them smooth and pretty.
If you have a belt sander or some sander with a circular sanding mechanism you can utilize this to make the sweet wheel cut-outs that all nice boards have.

Measure the trucks you want on your board and layout where you want them on the board so they are symmetrical on both front and back. Then place the trucks in this spot, make sure the right way (kingpins go from the ground up towards the middle of the board), and dot where the holes are for it. Most trucks go by the square pattern.

Though trucks come with different sized hard-wear, most will fit in a 15/64 hole just to make it tight and more stable.
Use this size drill bit to drill the holes and use the hard-wear to check the when you are done.

Take only the deck and coat the entire thing in any sealant, even any danish oil would do great, or you could even stain it. Just something to help the deck keep up against all the elements. Do about 3-5 coats, or continually while it dries, because it does pretty fast.

NOTE: if you are going to put a design on the bottom, do it after the first two coats have dried. Wood-burning looks cool and is easy to do. Or you can paint it. Or whatever you want. Just do it on a few coats and then put a few more coats of your finish on over it.

Step 6: Grip and Assemble

I recommend Gator grip. you can buy it online, it will run you about 10-15 bucks and is the best stuff on the market.
Get yourself some griptape, enough to cover your board, and lay it out on the board. Either use weights or a friend to hold it down while you take some smooth metal object, like a hammer to rub around the edges of the board, effectively creasing the griptape and leaving a white line of your board's outline.

Cut this out, lay it on your board, and make cut the little stragglers to make it perfect fit of the entire board.

From here you can cut out designs in your grip or do whatever you want. Clear grip also looks very cool on wood boards. Just make sure to 1 cut out the outline of your board and 2 cut out your designs before you put it on your board! Because you are not going to want to take of the grip once you have taken off the back paper and applied its sticky to the board

A COMPLETELY DIFFERENT APPROACH. You can buy some heavy duty appoxy and Apply it to the top of your board and while its wet you can sandblast it or just dump sand on it and press it in with a towel.

Assembly is easy and there are instructions for your trucks and wheels on video sites.
Just be patient and try it. Its much better and much more satisfying to ride something you've made. Especially since, if you do a decent job, it will be better than many boards on the market today for 200+ dollars, and totally custom =)
Have Fun, Hope this helped!

Shred Life
Crimson-Talons