Back panel I'll run downwards, base panel towards the back.So both into the back to base join.(Unless I forget or get confused!).

Forgot to mention I cut away some of the bulk from the corner before rolling and top stitiching.I don't often do it this way now as I prefer to just roll and top stitch leaving a raw edge to sink into the pile of the carpet.

10mm on seat faces if they're top stitched (pleats, diamonds, etc), 6mm bolster faces, 3mm for sides(normally only for backs not bases).

Pics are always better for me too.I learn a lot from upholsterers pics on instagram.I don't know if the above way is an official upholsterers way, I picked it up from a clothes sewing book.

Heres some pics I took a few years ago.My technique has improved since I took them although my photography skills haven't.

I think my 2 may be the same as Jesse's , your first and poss traditional tuck and roll (I'm in the uk so terminology may be different).
Glue 10mm foam to some calico and then as well as marking the lines use a razor to slice almost to the backing.The top material I then mark the lines and sew along them to help it fold.Foam on right , material on left, 1/8 inch right sided guide foot, align folded stitched material with razor cut and sew, roll material over to next cut line and repeat.
I have had lengths of clear plastic cut into one metre strips from one inch wide up to three inches wide going up 1/4 inch at a time.Makes marking out pleats a lot easier.

Three ways I do it.......... 1. traditional sew leather to calico, backfolding and sewing then stuff with padding.............2. Sew material to calico backed foam sliced along lines with 1/8 inch sa allowing extra for fulness and sa..........3.glue material to foam, cut into strips then sew together 1/8 inch sa allowing extra for fulness and sa.
For all above I first make a cardboard strip marked out to what I want finished panel to measure.Then do several test pieces to find correct measurements.
I normaly use my 1/8 inch edge guide to keep everything equal.

Ah, but we put our pants on under our trousers.

Looks like three sides have been sen up first, then the top ring, then lastly the forth seam.Forth seam won't be a french seam.

Pics are not mine but borrowed from instagram, apologies to who they belong to.Our thread sare just on a shelf.

We used some sort of drainage tube.Black plastic, about 12 inch dia, corrugated on the outside but smooth on the inside, think they came in 12ft lengths.

I drew my own designs up and had a friend who is a signmaker cut them out in polycarbonate(?).All were done as trades for work.Had about six or seven designs done though everyone stll goes for diamonds.Also had one metre strips made up ranging from one inch to 3 inch in 1/4 increments to easily measure up pleats, piping material, binding material and other uses.

I've done them the first of Gareths ways and it works well.Also I've come across mercs where the foam is longer than the material but comes out through a cut in the calico and isn't sewn through on the piping edge but hangs below.
Any idea Gareth on whats the best option for foam to stuff them with thats available in th uk?

As above, remove bolts and disconnect cable.

No where in particular just the cheapest on ebay.Not sure if the refils are the same as the space pen but they work although it takes a while for them to dry and they smear a bit, I try to use them only in non visible areas.This is typical of what I use:- https://www.ebay.co.uk/itm/100pcs-Leather-Silver-Refillable-Pen-for-DIY-Cutting-Leather-Marking-Sliver/162791137066?hash=item25e71b9f2a:g:Jg4AAOSwihVb5bts
These are the same as the white chalk ones I use, again I just get the cheapest.I like these better as they dry quickly and clean off well.Again I try only to mark in non visible areas or where it will be covered with a top stitch.When they run out you can refresh them a bit by adding a drip of water down the end cap.I prefer these to the silver pens but are more expensive. https://www.ebay.co.uk/itm/5pcs-White-Water-Soluble-Pens-Erasable-Cross-Stitch-Fabric-Marker-Pens/163349745846?hash=item26086750b6:g:mnsAAOSw-eJb5ScC

I'm in the uk but if you search for "silver leather marking pen" you should get results. Also try "white water soluble pen" these are my main choice for marking as it wipes off easily, dries quicker than the gel pens(I find they tend to smear) and won't get in the thread.

I use the chinese refils from ebay 100 for £4.Even better than gel pen refils but a little more in cost are white water erasable fabric markers, cost is £2.50 for 5 from china.

We use thin polycarbonate taped to the frame and closed cell foam.

Had mine set up and it seems to work a treat now.Test pieces skived great, next piece I tried was dash piece and found machine was great at skiving a chunk out of my finger, it also skived the panel nicely.

You can do it with square corners.

No it was secondhand,previously used for making leather wallets and bags.I did use a sharpie on the blade ,mainly to check that it was sharpened all round.I've seen loads of setting up videos, read most setting up instructions and asked on several forums but I just can't get it dialled in.I've moved the blade in and out, the stone up and down, adjusted the pressure springs on the stone (both tilt and up/down) but it just seems to cut too much or not enough, I can't get the fine adjustment.No one at our shop has used one before so getting someone who hopefully knows what their doing will be a benefit otherwise I've just got an expensive space filler.

Would you mark the piping up/measure the piping so it matches size of the pleats, ie once you've sewn the piping around the corner of the insert mark at 1 1/2 inches(or whatever) to lock the pleats to that size.

I have the global branded one, unfortunately I can't tell you how well it works as skiving machines are notoriously difficult to set up and I haven't managed yet.I have an engineer coming in a couple of weeks to set it up and show me how to work it.

Quite possibly you could use a low current switch that looks correct and use it to opperate a relay.

We just use normal thread.