I've now done a trial first moulding of the canopy which, although reasonable, could be better, as the moulded item shows minor signs of imperfection, indicating that the male mould could use another coat of clear varnish and more polishing.
However, for the purposes of test fitting, and to illustrate the process involved in moulding by this method, it will suffice for now.
After carving the male mould, and cutting the female from balsa sheet or other suitably stiff material, it is essential to obtain a glass-smooth finish on the male mould pattern, as any and all imperfections, in the way of grain, lumps and bumps or depressions will be transferred to the moulded part. This is not as noticeable on 'solid' plastic parts, but shows up easily on clear sheet.
PIC 1 shows the male mould sealed with a mix of clear gloss enamel varnish and talcum powder. When fully set, this is repeated as required, and then followed by two or three coats of clear gloss. (NOTE acrylic varnish is not suitable for this process.) This is then very lightly rubbed down and polished until smooth as glass.
PIC 2. A piece of clear plastic sheet, in this case approximately 1mm thick, is securely taped to the female mould, allowing a generous surround, to cope with stretch.
The female mould is then held under the kitchen grill, clear sheet upwards, at least four inches (100mm) away from the heat source (more if a gas grill) and gently moved around in a circular motion, until the clear sheets starts to become only just floppy. Any longer and it will rapidly sag and develop holes !
PIC 3. Moving quickly, the female mould is removed from the heat source and, in one swift movement, the male mould is plunged through from the same side as the clear sheet and held until cool. this takes only a few seconds.
PIC 4. For the purposes of this demonstration, a pic was taken showing the male mould in place within the clear moulded part. This may have contributed to the slight imperfections mentioned earlier, as it is a good idea to remove the male pattern as soon as possible, to minimise any possibility of the varnish, now quite warm, leaving marks on the clear sheet.
PIC 5. The clear part is now moulded.
PIC 6. The tape is removed from the clear sheet, and the part removed from the female mould. This can now be trimmed from the sheet, and the male can be re-inserted to act as a cutting guide if required.
Once I've trimmed the part, it can be checked for fit against the cockpit opening. If all is well, then i may still use this canopy, or possibly apply another clear coat to the male mould, re-polish and mould another part.
I hope this proves useful, and thanks again for the continued interest.