Hi Mike,
Nice to hear from you and glad your into modelling again, did you find Matthews missing Mojo???
Canopies, how we despair at times! I have done exactly the same thing myself in the past so I know how frustrating it is. One thing never use thinners on plastic clear parts, it always destroys them. What you needed to do was to sand off the offending overspray and then polish them back using micromesh cloth/pads of different grades until you get to 12,000 grit. They should be clear then to which you then dip in 'Klear/Future' to give a final lustre of the original.
Onto your current problem. With a Vac-Form canopy the best way to cut it out is as follows.
1. Use thin strips of Tamiya tape (about 2mm thick) to mark out the canopy or section of canopy you want to cut out. Ensure that the outer edge of the tape is as close to but very slightly outside the portion required. This will help you see where you want to cut much easier
2. Then taking a new scalpel blade gently follow the outer edge of the tape scoring the vac-form canopy.
3. Continue to repeat this a few times using a slightly heavier pressure on the cutting as you do so.
4. After a few passes the blade will start to cut through the vac-form canopy. Once to section has been completely cut and removed, remove the Tamiya tape guide.
5. Using a fairly fine sanding stick neaten the edges of the canopy (at right angles to the canopy edge). Making sure that the sanding does not infringe the outer edge of the panel required.
6. Then carefully and gently wash the section in warm soapy water to remove any Blood and sweat, finger marks etc. Dry on a soft cloth ensuring you do not press hard to stress the canopy.
7. Finally dip in 'Klear/Future' one or two times allowing each coat to dry before the next. Remove as much excess as possible though on each occasion.
Tip:- If the section is flat panel, you prop the panel against a tin or bottle whilst drying making sure only the very edges are in contact with the worktop and jar/bottle.
Paint and mask as normal, using whatever paint you prefer, the 'Klear/Future' provides a protective surface for all types. If possible apply masking tape to the reverse of the canopy part to prevent overspray. Remove this once paint has dried.
To attach to the model, you can use clear fix to attach, though ordinary PVA will work just as well. Vac Form canopies are generally a lot thinner than kit parts, so sometimes it is a good idea to glue some very fine strips of stretched sprue on the edge of the window aperture to form a ledge to help it sit in place better.
That's about it, Simples......................
Hope this works for you.
Did you ever consider contacting Eduard for a replacement canopy? Sometimes a quick email to manufacturer, explaining honestly your problem will result in a replacement part for free. They want you to buy more of their kits in future. It is worth a try.
Bigkev