You can spend some money on case tools. Just Google 'Stihl Case Splitter' and you'll see the general selection. I have the 'C' style Husky splitter which handles most jobs after the forks are spread slightly to fit over larger Stihl crank lobes as previously mentioned. On the other hand, it can be too big to sneak into some cases -- 041s for example. The 'L' shaped style with the additional attachments is probably the most versatile as it can also be used to pull cranks back into cases. They've been in short supply on the aftermarket due to Covid but seem to be coming back. Prices vary on those. I've had one on my list for awhile. The Stihl disk style is just a bizarre 'all-in-one' attempt at a cheaper puller for all their saws. The issue with those is having all the right bolts and figuring out the correct pattern for any particular saw -- and there are a couple versions of those last time I checked.
All that said, fashioning a basic splitter is butt simple and can easily be made with material you probably already have laying around. Angle iron, flat stock, 'c' channel..., anything rigid enough to not flex or bend. The example below is just a piece of uni-strut. Not the strongest way to go. but worked in a pinch when the Husky splitter wouldn't fit. I've since made another one from 1/4" aluminum 'c' channel that's much stronger. Some washers/spacers, a cheapie two-jaw puller and you're all set. Just a redneck version of the $100 'L' style.
Once the case is split,
then you can use a hammer (or preferably a press) to remove the crank from the remaining case half. I'm just not a fan of pounding a case apart when other less aggressive methods are available. If you do use a hammer to knock the crank out, take appropriate measures to not whack the threads..., a block or the clutch nut threaded on flush with the crank stub should suffice.
As for the clutch, I have the spanner set for the different sizes of clutches used on this era of saws. The one below just happens to fit a Homelite clutch, too. A piece of pipe may be necessary as a breaker bar to loosen the clutch. When they have them, I secure saws with stubborn clutches in a vise by their bucking spike to get more leverage on the spanner. A propane torch to heat the clutch carrier can come in handy as well. Using a punch and a hammer will almost guarantee you'll break shoes or the carrier.