I have a bit of a weird question.

I bought a BMW shape fibreglass kids car bed off ebay for $82. The paint was rooted.

My plan was to buy a few cans of metallic blue paint and give it a quick respray. Unfortunately I couldn't find a shop with more than 1 metallic blue can of paint in stock, so I ended up paying $45 for 500mL of automotive acrylic paint from Autobarn, plus thinners, sand paper, and other bits and pieces. The cheap car bed is getting more expensive.

I have painted it, it went on quite powdery. I think I had too much air or air pressure and it was drying too fast as I applied it. So it looks even more matte than normal.

I didn't want to pay another $60+ for an automotive clear to cover it. I also don't want a gloss finish clear as it will bring out the imperfections in the fiberglass, it is a bit wobbly in places.

I was wonder if I could spray on a satin finish clear house paint of some sort. There seems to be oil and water based satin clears. I assume a water based clear would be pretty safe to spray on and wouldn't react with the acrylic automotive paint?
http://www.bunnings.com.au/british-paints-1l-satin-water-based-clear-varnish_...

I want it to protect the metallic paint, so it doesn't scratch straight off when the kids drive matchbox cars on the paintwork etc.

This article has the following;
http://www.diynetwork.com/home-improvement/whats-the-difference-between-polyu...
"Both oil- and water-based polyurethane can be applied to latex/acrylic paint; however, oil-based polyurethane will create a yellow or amber hue, especially to light colors. To add durability without affected color, use a water-based finish."

So I guess I want a water-based polyurethane...

The waterbased clear would be the better option but get a tough floor clear it will hold up better

My only concern with a floor clear is they are designed to be self levelling and go on a horizontal surface. I am not sure how well they would spray and what it would do on vertical surfaces.

I used the water based satin clear varnish linked in my first post. $19 for 1L from Bunnings.

I had to thin it with 20% water to get it to spray on properly, it is pretty thick. It has stuck really well, no reactions. Seems fairly tough as the 2yr old climbed in and started driving matchbox cars all over the paint.