As said in my video, there are a lot of low hanging fruits.

The following improvements are made;
  - box is much smaller
  - photodiode flipped to opposite side (reduced size of box)
  - springs removed to adjust height photodiode and position first cylinder lens
  - added slit, simply clips all beams which are not refracted by prism

I changed the laser but want to move to a different housing, which is more compact and square. 

In the image you can see the new photodiode board.

I attached an image of the new laser module, I want to use. It is more compact and has a cube housing

Anyhow will be on holiday coming weeks, so you'll need to wait for completion :-).