Many of my past projects have thumbed their noses at convention or have been absurd, foolhardy or otherwise non-conformist, but this one extends the boundaries further than ever.

I'm going to try to make a boat by recycling plastic bottles.

Thanks to the assistance of friends and colleagues, I'm collecting up to a dozen HDPE plastic milk bottles a day. I give these a thorough wash and dry.

I'm also collecting upwards of 100 HDPE plastic bottle tops a week, which come in a wide assortment of bright colours.

I cut the bottle tops into quarters using garden secateurs and the bottles into long strips, which I then cut up into postage stamp-sized flakes, ready for the next stage. This is all hard work.

This is my drill-powered-drill-powered mincer. It's a traditional meat mincer, driven by an electric pillar drill, via the gearing mechanism of an old Stanley hand-powered drill.

I feed the quartered bottle tops and bottle flakes into this machine at a moderate pace and it grinds them up into small, manageable pieces.

I convert a carefully-weighed portion of ground plastic into a circular recycled 'pancake' by pressing it between two sheets of re-usable baking sheet (more details of this whole process on previous pages).

These pancakes are convenient to store - so I can just stack them up in a box until I'm ready to start construction ot the boat.

If permitted to cool too rapidly, or without being constrained flat, the pancakes tend to buckle.

I've discovered that by stacking a whole load of the plastic pancakes together from hot (but cooled enough not to be sticky), they can be clamped flat and the bulk stacking makes them cool slowly - thus they end up nice and flat.

Most of the plastic is just ground up together and mixed, which means the pancakes come out randomly mottled.

I decided it would be nice to introduce a bit more variety, so I also ground up some bottle tops grouped (more or less) by colour. I can add a pinch of these individually or in combination as part of the makeup of a piece and introduce a colour bias that I hope will make the end product look interesting.

The circular pancakes are welded together by clamping them in position, sprinkling a measured portion of ground plastic into the gap between them, covering with a sheet of reusalbe baking paper and ironing it all until fuse.

There will be a need to clamp flat again when I scale this up to the full build.

I did toy with the idea of trying to use recycled timber for the frame of the boat - I saw some that looked promising in a skip at the back of Debenhams in Portsmouth, but I had no way to get it home - and going back there with the car would have cost as much as just buying timber.

I don't need anything elaborate though, so I just got a few pieces of very cheap framing timber. If you take a little time to sort through the stack, you can often find lengths that are almost knot-free.

I ripped the framing timber into laths about 9mm thick on my cheapo table saw.

These will be thin enough to take the amount of bend I have in mind, but thick enough that I'll only need to laminate two of them together to make each of the bottom chines.

The laths aren't long enough though - so I cut some in half and joined the halves onto the full lengths with a scarf joint glued with polyurethane glue.

When I laminate the strips together, I'll make sure these joints aren't in the same place on both strips.

To join the plastic pancakes together, I arranged them on a flat board, heaped a little ground-up plastic in the middle, then ironed it all together with a clothes iron on high heat (through a reusable cooking sheet)

The weld is held down flat with another board and a stack of heavy bricks. This isn't a speedy process, as it needs to be repeated on both sides. but I'll get there in the end.

In what seems to be a continuous cycle of progress and setback, it turns out that the pancake-welding technique isn't scaling up well.

It's hard to get the right amount of additional plastic into the void between three pancakes - and getting this right means heating and reheating the same areas, from both sides - this causes the sheet to warp and buckle. Not good.

So I'm going to try a different approach that I considered earlier and has been suggested by others more than once. Cutting the pancakes into closely-fitting hexagons.

This is fairly easy - I made a sheet metal template, clamped it in place and scored around it with a heavy duty knife - then the edges just snapped off.

There's very little waste this way and the hexagons tile together very neatly. I'll weld them by applying a narrow heated bar to the joint - so I only need melt just enough to make the two pieces unite.

I needed a piece of metal that was fairly narrow, but thick enough to isolate the iron from the plastic, heat-conductive and fairly easy to work.

I rummaged through my boxes of junk, but found nothing suitable, but I knew I'd find something I could use at the Malthouse (see side column).

I ended up with a piece of aluminium bar cut from a cistern flush extension - absolutely ideal for the job. I cut it just a little longer than the sides of my hexagons.

By carefully aligning the bar on top of the butt joint between two of the hexagons, on top of a PTFE sheet, then applying the clothes iron, the metal bar conducts heat only to the joint - as well as loowing me to press down the melted area to force the edges to bond.

I did this from one side, then left it to cool (pressed flat with a weight) and repeated on the other side.

The result is a strong, neat joint that doesnt introduce any distortion to the piece as a whole.

It might be a little while until the next update on this project, but not because it's gone cold.

I'm busy manufacturing a stockpile of plastic hexagons - I'll do this until my supply of processed plastic is exhausted (or until I think I have enough to build the whole boat).

This is primarily for operational efficiency. I have limited space, so it makes sense to do a large amount of one task before clearing those tools away to do a different one.

So far, nothing is going to waste - using garden secateurs, I'm snipping the trimmings from making the hexagons into small squares, then mixing them back in with subsequent batches.

Continually remelting the same plastic can end up degrading it - so in order not to compromise the integrity, I'm only using about 25% re-recycled material - the rest is made up of the usual ground-up bottles and caps. This gives the panels a different look, but variety is good.

Update - November 13, 2011. The laminated framework is coming along nicely.

A couple more sessions and it will be complete - it can't all be done at once due to limitations of space (and clamps) - also, some of the structures don't reach final strength until the glue cures - it would probably collapse under its own stresses if I tried to build too much at any one time.

Update - November 18. The frame is complete.

It'll need sanding smooth and coating with a lick of paint, then I can start cladding it with recycled plastic panels.