I did a “single malt” scotch ale once by starting with golden promise, and making my own pseudo crystal malt, roasted barley, and oak smoked malt.
I used a toaster oven and a cookie sheet, and it worked quite well. The pseudo crystal malt smelled wonderful, but once I got to the roasted malt, it smelled similar to roasting coffee beans or burnt popcorn. I cold smoked with oak over night for the smoked malt. I bagged mine and let them rest for about a week before I brewed with them – you may want to give it two weeks.
I wish I could remember what temps and times I used, but I remember referencing some online sources for that info. Try searching home roasting or toasting malt to get a few sources. It was one of the best beers I’ve ever brewed, but I’m too lazy to try and replicate it.