Or, you could try this:
(defun C:SLOT (/ A B B1 B2 C D PW)
(setq PW (getvar"PLINEWID"))
(initget 1)
(setq B1 (getdist "\nLength of slot: "))
(setq B2 (/ B1 2.0))
(setq B (list B2 0.0))
(initget 1)
(setq C (list 0.0 (getdist "\nWidth of slot: ")))
(initget 1)
(while
(setq A (getpoint "\nInsertion point: "))
(setq D (list (- (car A) (/ (car B) 2)) (- (cadr A) (/ (cadr C) 2))))
(setvar "PLINEWID" 0)
(command "_.pline"
D
(mapcar '+ D B)
"_a"
(mapcar '+ D B C)
"_l"
(mapcar '+ D C)
"_a"
"_cl")
);while
(setvar "PLINEWID" PW)
(princ)
)
Add it to your Acad.lsp file, or type (load"slot") on the command line, or lcick Tools / Load Application and go tet it, or or or or ....