Hi! What are the best tools out there to simulate colours on your exterior?

Or, if you have any suggestions, how would you lighten this roof colour without washing out the exterior look? Keep the guttering and fascia dark and darken the garage door with a light roof? We would like to have a lighter roof colour for better heat transfer properties.

Tell me your tips or tools to do mock ups! Dulux on the phone today told me all about the tools they no longer have for me to use...very handy - not!

Pictured first is my very dodgy mock up of our actual house plan on an app my husband found with colours from our given colour scheme. There is actually weatherboard where the Mount Aspiring colour sits on the front, and on the windowless panel closest to the end of the house. (This app was fairly clunky). Mangaweka is the colour designated for render, but we're having Hardieflex so I plonked that colour on there for contrast, but they needn't be set that way. I could select either of those colours or a different one completely for the whole frontage, or retain contrasting colours. The garage door is surfmist which I don't think works with the other colours so well - more creamy/yellowy in natural light?? The soffits are surfmist too but that's pretty common. You can't tell, but gutters and fascia are same as roof at present with Woodland Grey. Below that pic is a picture I snapped of the only house that I've seen with a remotely similar colour combo, except with stained door (which I'd also prefer) and garage matching roof, rather than contrasting with it. I do love the nice contrast, but of course I'm trying to eliminate the dark roof, so I don't see how I could keep this contrasting dark garage against the lighter house frontage unless we make those windowless panels of the house a dark colour also and tie it in to the gutters and fascia or something...

Seventeen Mile Rocks Renovation & Extension · More Info

Above - greys that I'd prefer for contrast over Mangaweka.