Assembling the condensing apparatus was a fairly straightforward process; the only real difficulty was soldering the end pieces to the side tubes, ensuring all was square and that the cross tubes would not be too loose or tight once the ends were permanently fixed.
I found that the 40 other cross tubes were a bit of a tight fit but I eased these by filing a small amount from the ends of every cross tube. The tubes were spaced at 5mm intervals using two 5mm drill bits as spacers. Initially I set the assembly up vertically, pushing each tube down against the drill bits and adjacent tube while tacking with solder. After fitting a few tubes, I found it easier to lay the assembly on the bench and clamp the cross tube in place against the drill bits. After every 3 or 4 tubes were in place, they were checked to ensure they were square and the spacing was correct, repositioning the next tube to account for any discrepancy. It all went very well except that after fitting about 20 tubes I went off into a bit of a trance and soldered a tube where I needed to leave a gap for the safety valve. It took me nearly half an hour to remove the offending tube, rendering it unusable in the process; luckily there is a surplus of 4 tubes in the kit so there was no problem with discarding the removed tube.
Finally the removable roof section was temporarily taped in place on the roof and the tube assembly soldered to it, tacking it in several places.
The completed assembly is very sturdy and quite heavy.
Several coats of auto spray satin black were applied the next day as the top coat.
The condensing apparatus was then gently weathered with some 'NATO olive' and 'Anthracite' model spray paint.
Some of the shiny brass bits on the 'Bertie' power unit were painted with self etch black primer, namely: bolier bands, gas regulator body, steam regulator and the large plug on the top of the boiler.
The final finishing touches were the addition of name and number plates, a pair of TBLR company crests and a driver from Brandbright. The driver was painted using acrylics in the intervals between applying the spray paint to the loco. Coal was also fixed in the bunkers with diluted PVA glue.