It can be a difficult one when you don't have access to an oven. Often leaving it in the hot sun is effective but you do risk the resin sinking a little so best done before any final flat and polish. Heat mats etc can work.  The key is an even and consistent heat source for the duration of the post cure. 

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

Just an update for anyone else in a similar position.

I tried an amazon electric blanket, I then wrapped two duvets on top and weighted it all down to make sure it was making contact with all the bonnet curves.

It took a few hours to reach 45c so I reset the 9 hour timer and went to bed, when I woke up 8 hours later it had reached 57c so maybe with a thicker duvet (or potentially a third?) and more time I could have reached above 60. FTR the blanket only had a heat rating of around 35-40c - I gave the entire thing 14 hours and the bonnet was extremely hot to the touch but didn't appear to have any sinking so I'm guessing the heat didn't penetrate too well?

Luckily I chose the try before you buy option on amazon where they give you a demo one so it's being retuned. I have instead purchased some muscle therapy heat mats, the only downside is the biggest they offer them in is 100x50cm so I've had to buy 4. The benefit of these is they get a lot warmer and max out at 60c without insulation.. so hopefully with a duvet or two I can ramp these up to 70/80c.

I have made a carbon skinned car bonnet using the XCR resin system, the time for post curing is now required before a final block sand and paint.

Most bodyshops I have spoken to either want an entire full days rate due to their booth being taken out of action; or are generally pushing back.

I'm not sure if I should be considering heat lamps due to how the heat would be focused, I remember a long while ago reading about electric blankets though and began wondering if this would be a preferred method?

I had to fill the inside of the bonnet with a 2 part expanding foam to stop it inverting whilst under vacuum, this however is acting a bit like an insulator and therefore stops me from my original plan which was to post cure it using engine heat. I tried driving for an hour today and it was luke warm at best.