I prefer Shulgin's DMT synthesis using oxalyl chloride above all. It's really convenient apart from actually getting dimethylamine, as it is controlled. This video shows how it can easily be made simply, cheaply and in freebase form through hydrolysis of the amide in DMF with NaOH. You just need a pressure equalizing addition funnel and 2 flasks. DMF is cheaply available and used as a popular polar aprotic solvent.
video:
Also the oxalyl chloride can just be ordered online. It's also possible to make it yourself by bubbling chlorine gas (from HCl) through oxalic acid, but I don't recommend gassing yourself.
I'll also leave you Shulgin's method, straight from the DMT Tihkal entry if you are interested in doing this.
Tihkal entry: "(from indole) To a well stirred solution of 10 g indole in 150 mL anhydrous Et2O there was added, dropwise over the course of 30 min, a solution of 11 g oxalyl chloride in 150 mL anhydrous Et2O. Stirring was continued for an additional 15 min during which time there was the separation of indol-3-ylglyoxyl chloride as a yellow crystalline solid. This intermediate was removed by filtration and washed with Et2O. It deteriorates at a significant rate at room temperature, and should be used as soon as possible after preparation. The diethylether in this synthesis can be replaced advantageously with t-butylmethylether (TBME) which works well as a solvent in this reaction, but which avoids the potential danger associated with peroxide formation. The above indol-3-ylglyoxyl chloride was added to 20 g anhydrous dimethylamine in 150 mL cold, stirred anhydrous Et2O. When the color had largely been discharged, there was added an excess of 2N HCl, the mixture was cooled, and the resulting solids were removed by filtration. These were recrystallized from EtOAc to give, after air drying, 14.6 g (79%) indol-3-yl N,N-dimethylglyoxylamide with a mp of 159-161 °C.
A solution of 14 g indol-3-yl-N,N-dimethylglyoxylamide in 350 mL anhydrous THF was added, slowly, to 19 g LAH in 350 mL THF which was well stirred and held at reflux temperature under an inert atmosphere. After the addition was complete, reflux was maintained for an additional 16 h, the reaction mixture cooled, and the excess hydride destroyed by the cautious addition of wet dioxane. The formed solids were removed by filtration, washed with hot THF, the filtrate and washings combined, dried over anhydrous MgSO4, and the solvent removed under vacuum. The residue was dissolved in hot petroleum ether. On cooling, crystals of N,N-dimethyltryptamine (DMT) were formed, filtered free of solvent, and air dried, weighing 11.1 g (91%). There have been reports of byproducts from this LAH procedure when performed in Et2O that can compromise the purity of the final product. To obtain the HCl salt of DMT, the residue was dissolved in anhydrous Et2O and saturated with anhydrous hydrogen chloride. The resulting crystals were recrystallized from benzene/methanol to give N,N-dimethyltryptamine hydrochloride with a mp of 165-167 °C. The yield from 14 g of the amide was 13.3 g of the salt."
video:
Also the oxalyl chloride can just be ordered online. It's also possible to make it yourself by bubbling chlorine gas (from HCl) through oxalic acid, but I don't recommend gassing yourself.
I'll also leave you Shulgin's method, straight from the DMT Tihkal entry if you are interested in doing this.
Tihkal entry: "(from indole) To a well stirred solution of 10 g indole in 150 mL anhydrous Et2O there was added, dropwise over the course of 30 min, a solution of 11 g oxalyl chloride in 150 mL anhydrous Et2O. Stirring was continued for an additional 15 min during which time there was the separation of indol-3-ylglyoxyl chloride as a yellow crystalline solid. This intermediate was removed by filtration and washed with Et2O. It deteriorates at a significant rate at room temperature, and should be used as soon as possible after preparation. The diethylether in this synthesis can be replaced advantageously with t-butylmethylether (TBME) which works well as a solvent in this reaction, but which avoids the potential danger associated with peroxide formation. The above indol-3-ylglyoxyl chloride was added to 20 g anhydrous dimethylamine in 150 mL cold, stirred anhydrous Et2O. When the color had largely been discharged, there was added an excess of 2N HCl, the mixture was cooled, and the resulting solids were removed by filtration. These were recrystallized from EtOAc to give, after air drying, 14.6 g (79%) indol-3-yl N,N-dimethylglyoxylamide with a mp of 159-161 °C.
A solution of 14 g indol-3-yl-N,N-dimethylglyoxylamide in 350 mL anhydrous THF was added, slowly, to 19 g LAH in 350 mL THF which was well stirred and held at reflux temperature under an inert atmosphere. After the addition was complete, reflux was maintained for an additional 16 h, the reaction mixture cooled, and the excess hydride destroyed by the cautious addition of wet dioxane. The formed solids were removed by filtration, washed with hot THF, the filtrate and washings combined, dried over anhydrous MgSO4, and the solvent removed under vacuum. The residue was dissolved in hot petroleum ether. On cooling, crystals of N,N-dimethyltryptamine (DMT) were formed, filtered free of solvent, and air dried, weighing 11.1 g (91%). There have been reports of byproducts from this LAH procedure when performed in Et2O that can compromise the purity of the final product. To obtain the HCl salt of DMT, the residue was dissolved in anhydrous Et2O and saturated with anhydrous hydrogen chloride. The resulting crystals were recrystallized from benzene/methanol to give N,N-dimethyltryptamine hydrochloride with a mp of 165-167 °C. The yield from 14 g of the amide was 13.3 g of the salt."