I've made a few batches of tomato paste but it takes forever and you have to keep monitoring the pan to make sure it doesn't burn and it uses a lot of fuel.
But yesterday, quite by accident, we discovered a much better way.
Its glut time so I have been cleaning and quartering tomatoes and pressing them gently into 1 litre pots (mostly to get as much in there as possible) then freezing them till I can turn them into passata or soup or whatever.
Yesterday we took out a couple of the frozen pots and turned them out into a cooling roasting dish in the oven to let them thaw and forgot about them.
When we came back the piles of fruit pieces were still sitting in the dish, but most of the juices had run out, presumably because the freezer had burst all their cells and released the juice.
We carefully decanted off the almost clear juice and gently squeezed out a little more and kept it aside for stock or whatever.
Then I ran the pulp through the mouli to get rid of the skins and what remained was a thick, very tomatoey flavoured (ie it hadn't lost any discernible amount of flavour with the juice - which also tastes great) pulp, verging on the thickness of paste.
We used it as the basis for a sauce and the result was excellent. Thoroughly recommended.