1. Minimal example

CREATE OR REPLACE procedure test1 is
-- Minimal example
---------------
-- Default values:
-- Encoding: cp1252
-- Header: null
-- Footer: null
-- Margins: left: 1cm, right: 1cm, top: 1cm, bottom: 2cm
-- Interior cell margin: 1mm
-- Line width: 0.2mm
-- AutoNewPage: true
-- DocDisplayMode: fullwidth
-- Compress: true
-- DocTitle: null
-- DocObject: null
-- DocAuthor: null
-- DocKeywords: null
-- DocCreator: null
-- nopAlias: null

l_blob blob;
l_filename varchar2(30) := '123.pdf';
begin
plpdf.init; -- initialize, without parameters means: page orientation: portrait, unit: mm, default page format: A4
plpdf.NewPage; -- begin a new page, without parameters means: page orientation: default (portrait)
plpdf.SetPrintFont('Arial',null,12); -- set font attributes: family: Arial, style: regular, font size: 12
plpdf.PrintCell(50,10,'Hello World!'); -- print text: cell size:50*10
plpdf.SendDoc(l_blob); -- create content

-- print

/*
owa_util.mime_header('application/pdf',false);
htp.p('Content-Disposition: inline; filename="' || l_filename || '"');
htp.p('Content-Length: ' || dbms_lob.getlength(l_blob));
owa_util.http_header_close;  
wpg_docload.download_file(l_blob);

*/

-- or store
insert into STORE_BLOB (blob_file, created_date) values (l_blob, sysdate);
commit;
end;
/

Source: test1.prc

Result: test1.pdf