I'm going to make some wet lay moulds by hand using the EG160 tooling gel, EL160 resin and 450g carbon. I wanted to bag the moulds over night while the resin cures but want to know if regulating the vacuum is necessary? Does anyone have experience of using a regulator with hand laminating?
These moulds will be used to make parts in an autoclave. Obviously, tooling prepreg is available but the original part can't really be exposed to heat or pressure.

...I'll also make a mould using powder bound chopped strand mat and use it alongside the carbon mould to see how the fibre glass performs. It would be convenient if it works as it is easier to laminate with. Not sure CSM is the way to go on some of the larger moulds but might be ok for the smaller, flimsy motorcycle panels that I make.

Number of issues here:

1. Vacuum bagging moulds is totally pointless. Wet-lay vacuum bagging does not reduce void content, which is the primary concern for building moulds. Resin infusion and pre-preg are different stories, but vac bagging is purely done to increase the strength to weight ratio of the component, which generally speaking isn't a concern when building a mould. It doesn't matter if a mould is a bit heavy and resin rich, you aren't normally concerned about the weight.

2. I highly doubt the finished moulds will be suitable for autoclave use, EC may correct me here on the EG160, but composite moulds generally are not. You can get some toughened tooling pre-pregs that can be used in an autoclave, but wet-laid moulds with a gelcoat will very likely suffer under the combination of heat and pressure. 

3. The combination of fibreglass and carbon in a mould intended for pre-preg use can be troublesome. The different CTE between the two materials can cause lots of issues with warping and distortion.

I think it would help to vacuum bag them and that there's no reason to dial back the pump.  If you make sure you have a good bag stack and well slip jointed laminate and process material (peel ply, breather, release film) you should definitely get better compaction and less voids by bagging.  You will need a post cure to get the Tg of the resin high enough to use for prep-preg but this can usually be split between a supported postcure to whatever temp the mold will take followed by a slow ramped unsupported postcure off the tool to boost the Tg of the resin.  

You may have luck for small tools with chopped strand laminate.  I have made autoclave tools (low temp prepreg) from vinylester resin and chopped strand mat.  The key is getting good gelcoat and a perfect skin coat ply or the autoclave will punch the gelcoat into the voids in the skincoat backing ply and your parts will have little bumps on them.  Be careful that the CSM doesn't have a binder that makes it not compatible with the epoxy.  Regular light woven 200g cloth hand laminated in epoxy might be fine for small molds where CTE-mismatch isn't a big deal.  Make sure you roll it well with a bubble popper after each ply and use plenty of epoxy.

Interested to see how it comes out - good luck!