The 4mm acrylic plates I used are standard sized and glued, hence no cutting required. Source: http://www.plattenzuschnitt24.de. I spent roughly 35€ on all parts. The rear of the top lid will be covered with cloth.

I now added two versions of the door:

Door_print_assembly_AllCATPart_v2 has a 3.5mm gap between the door and the front face of the UM2 to make room for a rubber seal (http://www.tesa.de/consumer/tesamoll/tesamoll_eprofil_gummidichtung,c.html). Especially acoustic insulation is improved by this.

Door_print_assembly_AllCATPart_v2_no_gap has no gap in-case you do not want to use a seal of any kind (also worked fine for me).  

The door handle, hinges and corner pieces are printed.

For the holes I added a PDF template size A3.

Handle_v2_AllCATPart: I also added a second handle which closes with a filament (see picture above 'Handle V2') if you do not want to use a magnet to keep the door locked.

UPDATE: Just added to RAR archives containing individual parts for each version (request).

What you need

Acrylic sheets:
2 pieces: 0.3x0.3m (door plus to cover)
3 pieces: 0.3x0.2m (side pieces of top cover, rear is covered by a cloth)

Printed parts:
2x lower hinge (printed)
1x upper hinge (printed)
3x hinge shaft (3mm filament)
1x door handle (printed)
2x corner front piece for lid (printed)
1x corner rear piece for lid (printed)
1x corner rear piece for lid with screw holes (printed)

Rest:
2x magnets for door
4x 0.3m door seal
5x M3x8 countersunk screws
3x M3 nuts