alias putstuff var %a, %b = $regsub($1,/(\S)(?=\S)/g,\1 $+ $2,%a) | return %a

tidy and mine don't differ much, it kinda depends on what you're looking for.

On the string "this is a test":

tidy: t.h.i.s. .i.s. .a. .t.e.s.t
me: t.h.i.s i.s a t.e.s.t

Greets