lpr prints out, what is sent to it via STDIN. So you need to invoke
lpr for each file found by find:
find . -type f ! -name ".*" -print0 | xargs -0 lpr
-type f searches for files
! is a logical not, hence
! -name ".*" will omit hidden files (with some help from https://superuser.com/a/101012/195224)
-print0 separates the individual filesnames with
\0 so that this will also work with file names with white spaces in it.
xargs finally executes
lpr with the list of filesnames it receives (
-0 again tells that
\0 is used as a delimiter).
This command will list only non-dotfiles, but also those in dotdirs.
If you also want to exclude dotdirs, extend the
find command to
find . -type f ! -regex ".*/\..*" ! -name ".*"
And finally, as some versions of
lpr have obviously a problem with empty files, omit these also:
find . -type f ! -regex ".*/\..*" ! -name ".*" ! -empty
As a sidenote: To get a nicer layout of your printout (includes file name) you should consider to replace