Here's a build that's a little over $1000. I don't know what you like visually so the parts are just good value parts not the best looking/most cohesive, also it doesn't include a copy of Windows 10.

https://au.pcpartpicker.com/list/LjWWYr

On $1000AUD budget you're stuck with 8gb of RAM when you should probably have 16gb for CAD, but by going with a single 8gb stick you can easily upgrade by adding a second later on.

Ryzen is your best bet for CPU and motherboard combo for CAD due to the lower motherboard cost and the high core count on the CPU.

You mentioned CAD as the only thing that will require GPU acceleration of any sort. 1050 Ti a good low end GPU, you could go with a standard 1050 but it's not quite as good on the price to performance ratio.

On the PSU side if you want to save a bit of money you can go with a lower model to save money like the Corsair VS range but stick to the top teir brands like Corsair. A lower tier or no name brand can potentially kill your hardware or catch on fire.