I have been working on building a MM from parts for the last 15 months as a hobby. It has been a very challenging and enjoyable project. I didn’t work on it every day and usually only for a few hours at a time. Some weeks not at all. Any frustration meant quitting for the day. In retrospect, it has probably helped keep me from making any big mistakes. The first four months were spent searching for parts and building assemblies. Much time (most of the summer) was spent preparing the cab/head for decals, something that I have never done before.
Early on I came to the conclusion that it would impossible to build a MM without having one on hand to get some critical measurements in order to fabricate parts that were not available. The wiring harnesses would also be more difficult without a sample. Since none were near, I bought one with the thought to restore and sell it. My plan was to replace the playfield, plastic ramps, all three castle assemblies, all playfield plastics and posts, clear plastics, dragon/wings, side art, apron/backboard decals, trim, targets, updated Mantis castle gate assembly, troll assemblies, translite, DMD, coin door, lock bar, legs, glass, side rails and so on. As a matter of fact, the ball guides, metal posts, and wire ramps are probably the only parts on the upper playfield that aren’t new. The old parts would then be used with my own harnesses and other hand built parts to build a “player pin” to keep. This was my first attempt at a complete restoration. I don’t feel like I am in the same league with some of the restorers that are on the forums and would not call my restored pin collector quality or mint or anything like that. I consider myself just an average pinball enthusiast with some time and patience. I usually did a lot of research before attempting any portion and didn’t mind redoing something if it wasn’t right. This worked for me since I had no schedule to meet, and could play my other MM in the meantime to keep my enthusiasm for the project up. I'm really not a collector, so keeping a player type pin works just fine for me.
I bought a donor routed WPC- 95 pin (NBAF) to keep costs down and obtain some rare parts like the backbox lamp insert panel or tub (which had to be modified), transformer, speaker panel plus just a big supply of parts (flippers, slings, jet bumpers, ball trough, auto fire) , not to mention all of the WPC-95 boards. Only minor modifications were needed on the cab such as drilling a hole for the launch button and removing some cabinet wood so that the castle would clear like on the original.
I built the wiring harnesses myself from the schematics and using a wiring template/ fixture that I made. There were six major harnesses to build; solenoid/flash, switch, feature lamp, GI, backbox GI/flash, and opto. The original design has the feature and GI together but it was easier for me to split it into two. There are also some small harnesses for the drawbridge opto, back board lamps and plastic ramps. Sections of all NBAF harnesses were modified to work in the MM, especially the solenoid/flash. Overall, quite a bit of the NBAF wire was reused. My son came up with a simple tool to stripe (color code) wires. Exposed wiring for the ramps was purchased from BAA.
I also made the wooden side rail and back panel, hex posts, gearbox shafts, and other metal parts that were not available. There are 14 hex posts that had to be cut, drilled and tapped for 8-32 hardware. The two gearbox shafts were made with an improvised lathe (drill and dremel). There are 22 additional individual metal pieces that had to be fab’d. Fifteen were ball guides. All metal pieces had to be removed, measured, and put into CAD files. I wanted them originally high pressure water or laser cut but had to settle for plasma due to resource availability, not technical issues. A lot of time was spent polishing, grinding edges, and re-drilling holes in the 18 ga stainless. Every metal part had to be bent. Some were a lot more complicated than others. A small metal brake (18 in Harbor Freight) was used to bend the parts. Four wire ball guides were bent from 1/8 inch rod. (one was available)
A template was made in order to cut additional holes in the NBAF backbox insert panel so that the lamps would be in the same position as the MM.
I gave up looking for two of the wire ramps (I actually found a Peasant Ramp) and was practicing bending 1/8 in rod and then by luck found a metal sculptor who said he could duplicate the originals. He has made the Catapult and Right Wire Ramps with stainless rod. Up close, they wouldn’t pass as originals but they look fine in the player pin and the TIG welds seem to be a lot stronger than the original spot welds. Maybe later I’ll get these plated but they look pretty good in stainless.
At the present time the player pin is complete and running with the NBAF board set, new ROMs, used plastic and castles parts, used playfield and plastic ramps, all handmade harnesses, hand built metal parts, and the custom catapult and right wire ramps. I have not done a lot to this pin, basically a good cleaning , flame polishing the ramps, and replacing decals on the drawbridge and troll flaps.
The restored pin is also completed. It is being play tested to make any final adjustments. It is amazing how different a pin is with a new playfield. It is really fast and smooth. I can make shots much more easily than on the player pin.
Having been through this, I believe that a person with some moderate metal, woodworking/painting, soldering, and electrical skills could build a replica MM for under $7000 (minus labor- lol). It, of course, would not be as valuable as an original but would have many, many new parts as I have outlined in my restored MM link below. This estimate is based upon procuring each part from the lowest cost vendor, taking advantage of the good deals found at pinball shows, building assemblies rather than buying completed ones, finding a donor WPC-95 relatively inexpensive (under $1500), and having an actual MM close by. If you have welding skills and can fab the wire ramps, the cost would be a lot less. The time commitment is huge. I bet I have over 100 hours invested in wiring harnesses and over 100 hours in making/bending metal parts alone.
Recent part searches have led me to the conclusion that this project if started now would be a little harder (not impossible) because some parts are getting more difficult to find. For example, I can no longer find some lampboards. That results in the need to use individual IDC sockets for the feature lamps like Stern uses.
Big thanks go out to the vendors who have made parts available, especially those who remanufacture new parts. Also to all who post restoration tips/pics/ideas on the forums. (Clay’s DVDs and Bryan Kelly’s gallery of restoration tips were especially helpful.) Thanks to Gary Martin and Eric Schmitt who originally posted on RGP in Aug 2010 that a project like this was definitely doable and got me thinking.
I have over 1000 pics of the process and have included a portion in the link.
If any of you are ever around Frankfort Il and would like to see the player MM, contact me and stop by. There is a buyer for the restored MM and it is going to be picked up in a week or so.

The link to the pics is http://tinyurl.com/zll59yo (some date stamps are incorrect)

Wally

EDIT------For some reason Micosoft has shutdown my Skydrive account. I'll let you know when I get the pics back up.

The link to the photos used in my seminar at Pinball Expo on 10/18/12 is: http://tinyurl.com/jzjbhfw

First off thank you for all of the kind words. My Skydrive account has just been shutdown by Microsoft for some reason. I'll let you know when the pics are back up.
Gweempose, the two MM's do play differently. The restored MM with the new IPB playfield is faster and smoother. I have never played on a brand new playfield so I don't know if that is normal. The flippers have all new parts and coils and they seem stronger. I think that other differences end up being in adjustments. My son has been play testing the restored MM and has given me a list of items to "dial in". He is a "MM super fan" (I've seen him play for 8 hrs straight) These items for example are like "trolls need too hard of a hit to registor" So I have been readjusting things.
My homemade guides are not exact. They could be off maybe 0.010 in spots and I don't know if that is enough to make subtle differences.
I guess that I need more people to actually play both pins to give me their opinion.
PinballHelp, I removed each ball guide and carefully measured each with either a micrometer or a small metal tape. I did not "unbend" any originals. You have to measure the inner dimensions (or adjust outer dimensions for the thickness of the metal) because as you bend metal the "outer" metal stretches. Hope that makes sense. My daughter in law is proficient in CAD and was nice enough to take my drawings and put them into that format. Bending each piece took some thought because if you make some bends out of sequence the won't fit into the brake or vise.
Wally

Again guys, thanks for all of the kind words. I just wish that Microsoft would let me know why they have closed my Skydrive account without any notice so that I could get the pics back up.
Whysnow, I wouldn't worry at all about finding parts for your pin in the future or trying to "stock up" . It seems to me that parts which wear are available and will always be available. An example would be all plastic playfield parts. Also some parts which can break can also be repaired fairly easy. I've seen welds repaired on wire ramps that look better than the originals. Hope that makes sense. I don't have any spare things besides lamps, fuses, an assortment of screws and rubber rings. Wally

My account at Skydrive has been reactived (lets see how long it stays up this time) so for the time being the links to the pics are back working. Wally

PZY, thanks for putting the pics in dropbox. Wally

Ovfdfireman, concerning costs, I believe that a person (who has the basic skills and a MM nearby) could build a pretty nice replica for less than $7000 in parts. (based on the original conditions that I outlined) It would have all new parts with the exception of parts obtained from the donor such as flippers, slings, ball trough, auto fire, board set, cab/head ....... My project costs where a little more complicated since I essentially restored an existing MM and then built a replica with the used parts and homemade parts basically at the same time. So my restored MM costs are greater than 7K and the "player" replica was less. The time commitment is huge. If you look at your labor as a cost, the totals are out of sight. Also, if you include "beer costs" as a result of my br-in-law coming over to help me with bondo and painting, add another 1K.
Wally