To be honest those bits can be cut and assembled accurately with a hand drill and a cheap nasty jigsaw + scribe and ruler. The plastic supplier will cut it out for you to the right size to make life easier again.

I don't think you can laser HDPE anyway, so it'll have to be waterjetted = $$$. For reference i had 2x base and 2x top plates waterjetted from 4.5mm hdpe with the same amount of features and it cost $200 aud with me supplying the material.