There certainly is Michael, but it takes time - the average time for separating a canopy from the sheet is normally around 1 hour.
If you intend to separate canopy from windscreen, then it often helps to place a strip of masking tape, preferably the Tamiya type, as this has a thin, hard edge, over the cutting area. That is, either side of where the cut is to be made, on what will be the frame. This will provide a guide, and help prevent damage if you slip!
Once that's done, use a new blade in your scalpel (do not be tempted to use a saw, or any form of power tool !), and slowly, and carefully score around the canopy edges - do not exert too much pressure, and do not attempt to cut through the material in one go.
Continue to do this, scoring slowly and carefully at an approximate angle of 45 degrees, letting the blade do the work, until the canopy is free from the sheet.
BUT ! As you want to have a separate canopy and screen, make the cut between them first, using the same method as described above.
Once the parts are free, any slight roughness to the edges can be carefully smoothed by gentle sanding.
To add the frames, there are a few methods - painting as normal, or the use of tape or strips of decal.
Painting can be tricky, as sometimes the paint does not want to adhere fully, and will probably require a number of coats. Also, of course, this will mean masking on a difficult surface, due to it's flexibility.
Using painted clear decal strips, or painted clear parcel tape, such as ordinary 'Sellotape', negates the use of masking, and is normally easier to apply, and gives a more realistic appearance. Personally, I prefer using clear tape as, if it is incorrectly placed on the first attempt, it can be removed and then correctly placed. Once in place, it can be pressed down to ensure it is firmly fixed and, by dipping in 'Future' or similar clear varnish, the tape is then sealed to the surface. (once done, if anything other than a gloss finish is required for the frames, this can be applied with a fine brush.)
The method of preparation is similar for both tape and clear decal film - paint the interior colour first, onto an area of tape or clear decal film much larger than needed. Once fully dry, paint the required exterior colour over this. Once all is fully dry, cut strips of the required width, but longer than needed, and apply to the relevant area(s). Trim off any excess at the ends.
If using tape, lightly apply a length to a suitable flat, dust-free surface - I use an old, glass drinks coaster - then do the painting.
The pics below show the cutting on the canopy for my 1/72nd scale Halifax, but note that the scalpel is 'propped up' for the photo, and not at the angle used for the actual scoring.
Make sure you test fit the canopy and screen before any sanding or other trimming, in order to a) ensure it will fit (!), and b) work out how and where it is going to be attached.
If possible, use PVA (white glue) or Micro ''Kristal Klear' (which is basically heavier, refined PVA), to attach the parts and, once set, run a bead of the same glue around the joints, which will not only seal any gaps, but also provide a better 'hold'. This can be done by using the tip of a cocktail stick, running in a thin bead, and wiping off any excess with a wet finger tip, or the tip of a small paint brush, dipped in water, but shaken to remove excess moisture. If needed, a further bead can be applied once set, and this can be painted over if required. Alternatively, CA adhesive can be used at key points, but this (or the fumes from it) can fog the canopy. A dip in 'Future' normally prevents this, but can not be guaranteed.
Hope this helps, but if you're still unsure, don't hesitate to ask!