Currently there does exist a simple way to create trees (reify), but its applicability is limited to static templates with holes having statically known types. However when writing macros, there's frequently a need in something more sophisticated.
This is an open research question, and there are several possible approaches to solving this problem:
1) Classic quasiquotes that use string interpolation syntax: https://github.com/scalamacros/kepler/tree/topic/interpolation
2) TreeHugger-like DSL: http://eed3si9n.com/treehugger/
3) Improved reify that would work with partially typed trees