People have asked me how I made my shelter, so here is a summary:
Canvas: A rectangle approx. 7m x 3.5m with 3 eyelets in each side (in each corner and the middle of each side). You can use a different shape/size of course, ours is very large! This time I used https://tarps.cunninghamcovers.co.uk/16oz-cotton-canvas/quote but I have used ebay before as it’s cheap, just search for 16oz cotton canvas tarpaulin (12 or 14oz if you need a more lightweight option). Look for something water and flame resistant/proofed. Or you can make your own if you have a heavy duty sewing machine.
My 2 centre poles are 2600mm (cut in half for easy transport) and the 6 side poles are about 1850, again divided. They are made of about 46mm square softwood (hardwood would last longer, but I oil mine with linseed oil and they are doing fine). I bought 50mm steel box section (like this http://www.ebay.co.uk/itm/Mild-Steel-Box-Section-Square-Rectangular-Tube-SHS-RHS-ERW-/301940785329 ).
We cut the steel to about 200-250mm sections and slid half of it onto the top end of the bottom pole section. We then drilled through the metal and wood and put in eye bolts (we used M8) with plain nuts, marking the poles 1-8. Then you put the top pole as far into the box section as it goes and drill through that, adding eye bolts with wing nuts. Again mark the poles 1-8 so both the top and bottom section have the same number in the same face, as the holes won’t always line up if you swap them around. You want the wood slightly smaller than the box section at the top, if it rains you’ll struggle to take them apart if it fits perfectly, so file the wood down as needed. This does give you a bit of wobble when the wood is dry, so you don’t want to over do it either. A little wobble doesn’t interfere with the strength of the poles though.
We cut threaded steel bar like http://www.ebay.co.uk/itm/M6-M8-M10-M12-M16-M20-A2-STAINLESS-STEEL-DIN-976-LEFT-HAND-THREADED-BAR-STUD-ROD-/191770624873 (we used M10) into 150mm long sections, drilled a hole in the centre of the top of the poles and glued/screwed the threaded bar in. We then cut sections of the same wood as the poles to use as top pieces, drilled through them and added T nuts with a bit of glue (like http://www.ebay.co.uk/itm/T-Nuts-For-Furniture-Wood-Captive-Blind-Inserts-Four-Pronged-M5-M6-M8-M10-/252846976024).
The most difficult thing to find is possibly the centre pole (sorted by a metal worker friend). It’s made of thinner box section (about 25mm square), and made in two parts, one with a thinner end that slides into the other. You want the total to be the width of the canvas, but as canvas stretches and possibly shrinks, make sure you make the thin section extra long so you can push it together or pull it apart more over time (ours has stretched quite a bit!). You also want a hole drilled at each end, slightly wider than the threaded bar you’ve used.
Then we made the guy ropes out of 8mm polyhemp (like https://www.rope-source.co.uk/products.php?cat=8mm+Polyhemp ), using wooden rope runners (https://www.ebay.co.uk/itm/301715907895). I bought 100m of rope but didn’t use all of it, 50m might be not enough though. You need 2 ropes for each pole. your two central poles need to have longer ropes, mark these somehow so you can find them easily (I use bright ribbon tied to the wooden runners).
It is really important to have some really good tent pegs! I use giant army surplus ones or custom made large steel ones, but large wooden pegs work too. Don’t forget to bring a large lump hammer to get them in!