Here is an ebay link to a briquet maker: www.ebay.ie/itm/372951542630?hash=item56d5a4eb66:g:No8AAOSwfF1lAsak&amdata=enc%3AAQAIAAAA4Kur2sDs1OYtY1oRyxWOz97L9SsLzKRp8guWPdO4dIM30POmcjQh3NvHRwXumwPEohIO3hgRUOAXHLIn8djPsVGruhW7wg2ONvx8frm29xJm%2Fyd4xDEmptqeT8kq6cqN8sXdni4kAbTCKVKYC3Zek%2Bly9t35XYwIBarg9OLT2vhKhU6CPI%2FQDwcejx4wFzwssRVaa8Ibt6jdwhSM8%2BJyVdqLzMqeYe7kg%2FlE1j%2FV5fNhOHI7IdlSat2947o%2FZYGv7hP3b1WAYVUToZPg689vKkGVk%2BiuyrsxZc7isW5VGGfI%7Ctkp%3ABFBM_LCftdli
You're right, it's a very bad idea which will cause problems in the flue. Chimney fires become more likely, which in older properties can unfortunately lead to house fires too.
If you can smell products of combustion then you need to get your chimney swept. When used on a hot fire the smoke should all go up the chimney. Any smells in the room means potential carbon monoxide poisoning.