Step 1: Making Your Coffin - the Base
I don't have a picture, but first off I made a full-sized template of the coffin and laid it across seven pieces of wood. The template was then traced onto the wood, and it was cut to size
(you can see here where I stuffed up the side - unfortunately at the time all we had was a fixed mitre saw and a jig saw. The jig slipped a bit, but it's easily covered by the walls)
We made this coffin to a 1.5 metre length, with 350mm across the head, 600mm across the chest, and 320mm across the foot:
What you can't see in the picture is the three bracing struts - one across the head (inset about 80mm) , one across the chest, and one set across the foot (inset about 160mm) These were screwed straight across all boards.
Step 2: Making Your Coffin Three Dimensional!
This set up gave us a depth about 8cm taller than a becks beer bottle - allowing plenty of space for the water, ice and beer.
Here you can see my lovely partner getting the walls up, pilot drilling with the dremel, then attaching countersunk screws straight through from the exterior. :)
Once you have the walls up, simply putty over the lines and screws. At this point I also put the bung hole in it - using a bung from an old hot water bottle and a spade bit, we now have a way to drain it. (White plumbers tape will help for a snug fit if you overshoot)
As we used pine decking, we also sanded out the ridging on the exterior and around the bung for a smooth surface. Looking back, I would have gone non-ridged, but hey, MGP10 decking is cheap
Step 3: Painting
After this, we went over it again with some aged teak, which when dried gave us a suitably beaten up look.
Step 4: Lining and Waterproofing
Once this is done, I went over the staples with Selleys All Clear (polymer sealant) This was applied mostly by hand (WEAR GLOVES) and smoothed to be not-too-obvious. When this had time to dry, we did a test run, then isolated any leaks and re-sealed them.
The bung was cut in a four-strip diagonal pattern across the hole, then sealed down into the hole itself to prevent leakage under the tarp.
And voila! You're done!
We fit five bags of ice and four boxes of beer into this without a worry, and using Fungus Amungus' Frosties idea, it came out brilliantly.
When finished partying, simply pull the bung and drain it into a bucket for use on the garden :)