After several months of prevarication I finally splashed out on a plotting cutter. It's a Silhouette 4 which is supposed to be the best of the home/desktop cutters. You download Silhouette's own Studio software for creating designs and sending plots, although as I'm a daily Autocad user that is my preferred platform to work with. The software allows you to import dxf format files, which is a doddle to create in Autocad. I had to work out that if the dxf is saved full size then Studio will read it full size. So for instance if you wanted to create masks for a 1/72 model, then you need to draw the designs at 1/72, simples! One snag was that some objects were appearing as folded up and out of shape in Studio, but I correctly deduced the software was not sophisticated enough to read closed polylines (CAD dudes will get it) and after exploding them all was well. When it came to sending a plot I found the software less than intuitive, but got there in the end and after a first botched cut managed to produce a set of wheel masks for my Crusader build.
My first attempts at cutting were somewhat farcical, but I succeeded in not throwing the machine out of the window. The Studio software is not intuitive, which is half the problem. The lack of clear instructions is the other half. I spent a fair bit of time Googling and watching vids, and finally the penny began to drop. Drawing designs is not a problem (that's my day job) and Studio reads dxf files so I can do stuff in Autocad. I needed some circles for masking tank wheels as mentioned above, which were very easy to draw, but I couldn't get a plot to send because the cutter was not 'reading' the registration marks on the cutting mat. Eventually I realised I wasn't positioning the media correctly and finally got a cut. Then I saw on a vid that is was a good idea to cut backed vinyl without a mat - using the mat as little as possible keeps it sticky for gripping media. First off I had probs loading the media, then after sending the plot it was trying to find non-existent registration marks. Then I thought 'what if you switch off the marks in the software?' It doesn't tell you that anywhere, but bingo, it worked. Now feeling more adventurous I replied to a request for masks on another forum, registration letters for a privately owned JP5. Easy peasy!