One of the more annyoing things about reincing into merchant is grinding up chest creation from that 70%. I have found one way to do so that is relatively easy and uses plentiful materials. To grind the skill, I'd suggest starting with medium chest skeletons. They are available at the hardware store in Arelium and in Esiris, and can yield up to a 7-slot chest. This gives you some usable sized chests to sell or keep once you are done.

The procedure is quite simple. Build chest hulls with wood and reinforce with ebony. Thats it. Build until you get the max message for hull: The construction looks very big and sturdy. And the max message for reinforcements: Just a final touch and the reinforcement is fully complete. Then finish the build. Repeat until you have chest creation showing at 100% in "grep 'Chest creation' merchant info 25"

Each medium skeleton will take about 900 kilograms of 'wood' material and about 500 kg of 'ebony' material. With lift of load you will probably be able to carry 100kg pieces of material without any problem. Your material usage may vary depending on any (very annoying) fumbles and whatnot that all merchants have to deal with.

Chest/Coffer hull progress
It looks totally incomplete.
The basic structure is forming up.
It slightly resembles a chest.
It is missing a lid.
It is still quite shaky.
It looks like a small chest but it could be so much more.
It does not look quite safe yet.
The base looks strong now, but the lid is still quite weak.
The chest is looking much larger.
The construction looks bigger and bigger.
The structure is now stronger than ever before.
The chest looks big enough to hold out several equipments.
The extra material has made the chest almost impossible to breach.
The chest construction looks quite large and safe.
The extra material in support-structure guarantees quality.
The chest looks just perfect and there is very little unfinished.
The construction looks very big and sturdy.
(Substitute in 'coffer' for 'chest' when building a coffer)

Chest/Coffer reinforcements progress
The reinforcement looks totally incomplete.
The reinforcement is still quite weak.
The structure looks much stronger because of the reinforcement.
The reinforcement still lacks quality.
The reinforcement looks fine but it could be improved.
The reinforced chest looks quite sturdy now.
It would be a pain to force through the reinforcements.
Just a final touch and the reinforcement is fully complete.
Yes, the above message is the final reinforcement message even though it looks like it can go further, it won't
Also, again substitute 'coffer' for 'chest'

Chest/Coffer lock build progress
The lock looks totally incomplete.
It slightly resembles a chest lock but much needs to be done.
The basic structure is forming up quite nicely.
The inner structure looks almost completed.
The lock still lacks all the rolls.
The lock looks somewhat ready.
It looks like a primary lock but it could be so much more.
The extra material in mechanism should pay off.
The lock looks very complicated.
It looks very strong, almost impossible to break.
The mechanism is now stronger than before.
The quality of lock is very high but dials could be more sturdy.
The lock looks extremely strong and supreme quality.
The lock looks incredibly strong and of divine quality.