About a hundred years ago, there was a push to create more "Estonian" grammatical forms, to lessen the influence German had on the language. This is when many analytical verb forms (the ones with multiple words, such as have been doing) into synthetic forms. Some people took it further and condenced entire clauses, and the maks-clause was born as a result.
The maks-clause is a replacement for the purpose clause. The regular purpose clause uses the subjunctive et with a da-form of the word: I went to the kitchen to make tea > Ma läksin kööki, et teed teha. The maks-clause doesn't use a subjunctive, just the form: Ma läksin kööki, tegemaks teed. There's nothing outrageous about the maks-clause, but it often feels kind of forced, so it should be used sparingly.
*Incidentally, nominalisation can also be used to mark purpose, but note the word order and change in case for tee: Ma läksin kööki tee tegemiseks.
