Unfortunately, the R3000 doesn't have the ability to do 3" core rolls due to the limitation of the 13" roll canvas thickness. There are a few brands that do 13" rolls with the 2" core, but not much of canvas...more of paper.
I understand the weight and size can be an issue for you since you're retired. The next option would be the Epson Stylus 3880. It's about 50 lbs, but it doesn't have a roll attachment. However, you can still print from a roll while having a way to keep the roll in the back and feed from the back feeder. This way, you won't have to worry about the core size, but it will print a bit easier than the R3000 and has larger inks. Although it doesn't have a cutter (R3000 doesn't either), there are paper cutters available. We do carry the printers, papers/canvas and cutters as well as stretcher bars if you're interested in taking a look at the selection.
I hope this helps in a way.
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