Mahogany Homes
For me, there were 2 stages to construction training with mahogany homes. The first was oak plank contracts using the Varrock sawmill before Song of the Elves is completed, and the second was teak plank (adept) contracts after Song of the Elves using the Prifdinas sawmill. Depending on which trees you are sourcing your logs, it can be good to do this on the Forestry world (444).
Items needed
Axe, pickaxe, saw, superheat runes, teleport runes, Kharedst's Memoirs/Book of the dead or a dramen/Lunar staff. Planck sack (Mahogany homes reward). Ring of the elements if going to the Varrock sawmill. Ardougne cloak
Getting to the Varrock sawmill
Ring of the Elements earth altar teleport, but if you don't have that, teleporting to outside the Taverly POH and taking the balloon transport system to varrock is another way
Sourcing steel bars
Use the Ardougne cape to teleport to the Ardougne monastery, mine the coal and iron outside and use superheat to make steel bars
Getting to Hosidius
Book of the Dead/Kharedst's memoirs or teleport to Grand Exchange for the fairy ring.