Try this will need a couple of changes like offset value and hatch settings, supports the boundary is on more than 1 layer eg sides & back may be different to front.
; hatch a strip inside a closed area
; By AlanH July 2021
(defun c:hatstrip ( / off ss lays x pt pt2 ent1 ent2 co-ord oldsnap oldlay)
(setq off 1.0
oldsnap (getvar 'osmode)
oldlay (getvar 'clayer))
(if (not (tblsearch "Layer" "HATCH"))
(COMMAND "_layer" "_m" "HATCH" "_c" "171" "" "_lw" "0.15" "" "")
)
(prompt "\nPick objects for outside 1 is ok more for multi layer ")
(if (setq ss (ssget))
(progn
(command "layiso" ss "")
(setvar 'osmode 0)
(setq pt (getpoint "\nPlease pick point inside"))
(command "bpoly" pt "")
(setq ent1 (entlast))
(setq co-ord (mapcar 'cdr (vl-remove-if-not '(lambda (x) (= (car x) 10)) (entget (entlast)))))
(setq pt2 (polar (nth 0 co-ord) (angle (nth 0 co-ord) pt) (/ off 2.0)))
(command "offset" 10.0 ent1 pt "")
(setq ent2 (entlast))
(setvar 'Clayer "HATCH")
(command "-hatch" "P" "ANSI31" 1 0 pt2 "")
(command "erase" ent1 ent2 "")
(command "layuniso")
)
)
(setvar 'osmode oldsnap)
(setvar 'clayer oldlay)
(princ)
)
(c:hatstrip)