The pinball machine case will be made from plywood of 2 cm strength. Please note that, after actually buying the wood, I do no longer consider this kind of wood "cheap". Not at all - the price per square meter was around 40 Euro.
At present, I plan the playfield to be 109 cm long and 60.5 cm wide, which seems to be a regular size at least for the top glass. The case is currently being painted with dark blue-metallic car spray paint ("Dupli-Color Acryl-Metallic Nr. 120-0400"), then will be airbrushed.
The case will consist of two parts, just like commercial pinball machines: A lower box containing all the non-playfield parts like the controlling PC, I/O and power supply subsystem. The playfield and the parts belonging to it (like bumpers, holes, and ball launcher machinery) will be mouted to a frame that can be folded up for easy access to the parts in the lower box.
The lower box will be 50 cm in height, the upper box 40 cm so that, should I not change the plan later, two playfields can be put into it.
The case will be 65 cm wide and 135 cm long on the inside. This leaves 25 cm space on the box top for backbox installation.
Lower box, the upper playfield box, and the backbox must be connected by plugging cables only, so that easy disassembly is possible when the machine has to be moved. The wood alone is quite heavy. Also, the sheets of wood should not be glued together in any way, so that they can easily be taken apart. It looked like I will have to do this to ever get the finished machine out of the room where I am going to build it.
I am documenting the building process in a /PhotoLog.
The playfield will have (at least partially) two levels. The lower level is where the game starts and where most of the active elements will be. It will also contain a ramp (or a kind of elevator, I am not quite sure about this yet) to the upper playfield.
Either the lower level only or both playfields will have a variable angle and therefore variable ball speed. The angle can then dynamically change between 3 and 10 degrees. Usable values for playing have to be found by testing, but "professional" modern pinball games use an angle of 6.5 degrees, where older ones used 3 degrees.
Goal of this is making the game faster (that is, make the ball faster) as the player becomes better. Basically, the more points a player is awarded, the faster the ball shall roll, making it more difficult to reach even more points. Care must be taken, though, that the game does not become unplayable. Therefore, the DPA must be taken into account when planning the mechanics specifications.
The lower playfield will be based on plywood, painted blue first, then airbrushed, then covered with two or three coatings of clear acrylic varnish.
Before painting the playfield, holes for the game elements (as bumpers, targets, lights and things) have to be drilled or sawn, but I think I will insert the inserts for these holes after painting the board, depending on their colour.
The upper playfield will be made of perspex. I have seen photos of Zaccaria's "Pinball Champ", which uses this for a small upper level, but at the moment my plan is to have a full-size upper playfield. I will somehow have to find out if it is possible to build mechanic game elements (e.g. bumpers) into this, though. If not, I will have only flippers and some targets in the upper level, just as "Pinball Champ" seems to have.