Whatever you do, don't use 15x15 extrusion, it's far too small for scaling to the size you want and you will end up with a wet noodle for a frame.
There are some upscaled Kossel parts out there as Forerunnert said.
The SeeMeCNC is actually nicer in person than it looks in pictures (nice guys too), but I too dislike the wood (the smell makes me ill).
Along with the Kossel, is the Wolfstock designed specifically as a large delta, and the Griffin, which was designed specifically as a scaleable delta. There are carry on luggage size Griffins all the way up to 1meter tall Griffins, with larger ones being built, though I don't really recommend it. If you want to go over 1000/500 (h/w), I would recommend a Wolfstock and it's 20x40 for a bit more rigidity. The stiffer your frame the better.
Even if you don't build a Griffin, there are a lot of resources there for those building and designing large deltas. From design considerations to available glass, heaters and diagonal lengths as well as some parts you can use on other 20x20 designs, such as extruder and electronics mounts.
There are some upscaled Kossel parts out there as Forerunnert said.
The SeeMeCNC is actually nicer in person than it looks in pictures (nice guys too), but I too dislike the wood (the smell makes me ill).
Along with the Kossel, is the Wolfstock designed specifically as a large delta, and the Griffin, which was designed specifically as a scaleable delta. There are carry on luggage size Griffins all the way up to 1meter tall Griffins, with larger ones being built, though I don't really recommend it. If you want to go over 1000/500 (h/w), I would recommend a Wolfstock and it's 20x40 for a bit more rigidity. The stiffer your frame the better.
Even if you don't build a Griffin, there are a lot of resources there for those building and designing large deltas. From design considerations to available glass, heaters and diagonal lengths as well as some parts you can use on other 20x20 designs, such as extruder and electronics mounts.