Ever regret doing something during a build.

My only near equivalent of this is drilling out holes in the metal frame of a diesel engine in order to accommodate extra wiring and the use of a different (MTH for Lionel) body shell. Metal filings and dust accumulated everywhere around the work area except the main boards, which I had masked off. Unfortunately this did not protect a speaker and the magnet in it attracted many bits that were not easily removed by vacuuming. Fortunately about half a day of manual cleaning - the longest part of the job - removed enough such that the sound was not affected. 

Oh Yes - big mistake. When I built the benchwork for the layout in my attic, I did not leave enough room to easily access the back part of the layout. To get to the accessible half, I have to squeeze, twist, and bend to get by and work in front of the rafters. To get to the less accessible half, I have to remove boxes from under the layout, pull myself up onto the floor backwards from the stairs, and slide back in a sitting position. Then, I can get my two arms and head above the layout surface to service track and equipment – the two-handed job is difficult. In some cases (derailments), I can get to the area by standing on the floor above the steps and lean over - in this case, I have to hold onto a support I made between two rafters - then I have only one hand free I have thought of trying to pull the layout outwards (needing extra help); however, I am concerned that I would cause more problems and work that I would not like to handle. Alfred There is a lesson in this –think and do planning before you start building , consider access points, and assess and reflect during the build.

Well now problem 2 has arise. I can either run the EM1 the oppisite direction than I normally do ( which isn't a big deal ) or I have to rearange the whole bridge thing somehow as it is hitting the entrance because I only have about 2" prior to entrance and need about 4". I could run it on inner loop but then I would take the chance that what ever I had on outer loop getting knocked off the track when they passed each other at the entrance to the bridge. So I guess it's going to be run it in oppisite direction from what I have it set up for at present. I also could make O gauge on the outside and run one loop of SG through the bridge but that just would not work for my plans.