If you are handy with fiibreglass, can cut, thread, form and weld metal, and prepared for about 50 hours of work consider this as a project. Now you have either pull your "rubbish wheelie bin" out of service for a couple of weeks or do it between collection cycles! I used the inside of the polypropelene bin as a mould. The bins come in a few sizes... I used the 450mm square mouthed model, made it 450mm deep and 200mm wide. I cast the flat panels on metal smeared with PVA release agent. The total thickness of glass is about 5mm, gelcoated first, then next day the fibres... first tissue weight, then 1.5 ounce, then 2 ounce weight, then woven rovings. The boxes would weigh about 3 or 4kg each. Give the lid to box 4mm of clearance. To join the panels I used auto fibreglass patching compound, David's P40, made in UK. Grind the cast edges first to remove the wax which comes to the resin surface. To make the boxes lockable I fabricated 2 stainless steel rods, threaded one end, and welded on a slide fitting bush to the other, then welded a dia 40mm ring to the welded bush. I made 2 "ring nuts" made from welding dia 40mm ring to the 20mm long threaded bushes. Use the metal lathe to drill the tapping and clearance holes in the bushes. Re-tap the bushes after welding to restore the thread which has "weld shrunk". Tilt out the rings away from the box before welding them to the threaded bush so that the turning "ring nuts" clear the tapering lid, about 15 degrees is fine. The bars are 10mm. Where the stainless bars enter and leave the top lid flanges, fit 40mm square stainless plates, 1mm thick is fine, with 12mm holes in the centre so that the pin bushes don't bite into the glass, and so that the lid flange cannot be easily cut through with a hacksaw. Lid flanges are 45mm deep. Go to your industrial lifting sling maker and get some plastic coated cable diameter 8mm cored steel cable and get 2 slings made with "soft loops" of 200mm each end. The cable passes through the two steel rings then through the rear rack or other part of the bike frame. Use heavy generic padlocks. My KLR 650 needed 2 slings each measuring 1300mm overall. The lid is locked to the box and the box to the bike, it looks locked and the whole box can be removed in a minute. I will use 32mm wide luggage tapes with 5mm stainless steel hooks each end with spring loaded catches to clamp the boxes to the frame, one "east west" and the other "north south". I fibreglassed electrical oval profile pvc plastic conduit to the inside of the tops of the lids to guide the 10mm rod through the lid. Use self adhesive rubber strips to the contacting surfaces of the frame to the box so that the vibration doesn't cut the fibreglass. The pics will help answer issues about scale and assembly.

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Nice job!
To play devils advocate what will they be like for impact damage? I do have the unnerving habit of throwing my bikes and myself in strange directions when I hit loose sand, mud, oil etc...
I remember fibreglass kayaks as being a bit prone to cracking when you hit a rock etc and this put me off thinking about fibreglass as something to fabricate boxes with.

Yes, point taken, but thinking about it, cars have fragile panels and even street ones have bumpers... off road ones have a perimeter cage of some kind. I have the perimeter of the frame extending a little from the box, and gave all corners generous radii, giving some "skid ability". Other than that, or as well as that, I suppose you could build the boxes 5mm thick like I did, and give the leading and bottom edges rounded profiles to enable the bike to skid rather than crunch. If you really wanted a stronger walled box, and can source the material, use carbon fibre for reinforcement and epoxy resin as the binder. I have a couple of Ford auto polypropelene fuel tanks, never used. They are 5mm thick, are co-extruded, are tested to destruction, and have better impact resistance than steel and aluminium. All you have to do is cut off the extending pod, make a pair of cradles to stand them up, and fabricate a pair of top lids. Easy for tech teacher like me! But I've done enough for now...I'm off to the US in 2 weeks and have enough to do! Cheers from Australia! Steve.

am saving up for the oven so that I can start fabricating carbon fibre panels, apparently the one I roast the chickens in is a bit too weedy! The CFE (Carbon Fibre Elefant) will be one sweet overlanding bike.......

What is the script with using kevlar and epoxy?

Those of you with longer memories may remember Craven panniers and they were all fibreglass (although I think the really early ones may have been wood!). They were the market leaders in the UK for a couple of decades in the 60's / 70's supplying the police etc.

They were pretty tough with ours surviving quite a few scrapes down the road. I still use some of the mounting brackets on my current diy overlanding panniers.

Nice job.

Another method if you want really strong and light is cored composite.

Make your boxes out of 5mm marine ply with the joints just tacked with epoxy. Coat all surfaces with epoxy then fillet the internal corners with epoxy mixed with very fine wood dust (the stuff in your belt sander collector bag works great). Grind the external corners to a radius then lay up inside and out with biaxial glass cloth using epoxy resin NOT polyester.

This method of construction is used to make the boats that nutters row accross the Atlantic in.

You could use a foam core but you would need to use more glass. Ply with glass both sides in very strong. You will struggle to put a hammer through it if you tried.

If you want a bigger radius on the outside, you can build the corner with a timber angle then run a router around the outside before glassing.

Absolutely brilliant. These ideas are what made the British Empire, using the bin as a mould, priceless!.

I made myself a canoe using this method. Regularly pound the poor thing off rocks etc. in rivers, seems to take no harm. It's also very easy to repair. Just patch it with some glass mat and epoxy. My understanding is that epoxy, while much more expensive, is MUCH stronger than the polyester stuff they use for car repairs etc.

I reckon you could make some really nice panniers this way. To build my canoe you sew it together first using copper wire, then tape the joints with fibreglass tape, then cover the whole shebang with glass cloth. This would be a good method of making the panners too as by sewing first with copper wire you can introduce curves into the construction, making it much stronger.

I think if I was going to do this I'd leave them unpainted. The glass-fibre mat goes clear when you epoxy it. Wooden panniers wood look fantastic! (and just a wee bit different!)

Nice panniers tenere-rider. Good effort thinking 'outside the box' as it were!

Matt

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*Disclaimer* - I am not saying my bike is better than your bike. I am not saying my way is better than your way. I am not mocking your religion/politics/other belief system. When reading my post imagine me sitting behind a frothing pint of ale, smiling and offering you a bag of peanuts. This is the sentiment in which my post is made. Please accept it as such!