i'm guessing you can add dilute solutions of sodium fluoride and calcium chloride dropwise to a large beaker of water being constantly stirred, with a seed crystal in it? fluorite has a very non-negligible water solubility of 15 mg/liter and a reasonably high melting point, so intuitively i'd think this should be easy and fast
maybe the ingredients are hard for you to get tho, in which case you might be reduced to generating hydrogen fluoride from fluorite and an acid, then bubbling the gas into the beaker
the standard industrial method sounds like it would be pretty annoying to do in your garage:
> However single crystals for industrial applications are usually grown by solidification from a melt. The so-called Stockbarger-Bridgeman and the vertical gradient freeze processes are used for industrial manufacture of single crystals. The crystals are grown in a drawing oven and in a vacuum of 10^-־4 to 10^−5 mbar in the Stockbarger-Bridgeman method. A crystalline raw material is melted, so that a homogeneous single crystal is obtained with exacting control of temperature.
> In order to make the single crystals up to now the crystalline raw material is slowly heated in a vessel to the volatilization or evaporation temperature of water of about 400° C. and is maintained at this temperature in order to keep it free of water for some time. Additive scavengers, such as PbF2, SnF2 or ZnF2, are used to remove oxygen from the raw material. The added scavengers react with the oxygen present in the raw material and arising partially by oxidation and/or hydrolysis to form easily volatile oxides, which escape at these temperatures. After that a so-called refinement during a single week at 1450° C. usually is performed followed by a multi-week cooling to about 1200° C., in which the desired crystal is solidified from the melt. The single crystal so obtained is then cooled in a first slow cooling phase and then cooled to room temperature in a second accelerated cooling phase after the first cooling phase.
maybe the ingredients are hard for you to get tho, in which case you might be reduced to generating hydrogen fluoride from fluorite and an acid, then bubbling the gas into the beaker
the standard industrial method sounds like it would be pretty annoying to do in your garage:
> However single crystals for industrial applications are usually grown by solidification from a melt. The so-called Stockbarger-Bridgeman and the vertical gradient freeze processes are used for industrial manufacture of single crystals. The crystals are grown in a drawing oven and in a vacuum of 10^-־4 to 10^−5 mbar in the Stockbarger-Bridgeman method. A crystalline raw material is melted, so that a homogeneous single crystal is obtained with exacting control of temperature.
> In order to make the single crystals up to now the crystalline raw material is slowly heated in a vessel to the volatilization or evaporation temperature of water of about 400° C. and is maintained at this temperature in order to keep it free of water for some time. Additive scavengers, such as PbF2, SnF2 or ZnF2, are used to remove oxygen from the raw material. The added scavengers react with the oxygen present in the raw material and arising partially by oxidation and/or hydrolysis to form easily volatile oxides, which escape at these temperatures. After that a so-called refinement during a single week at 1450° C. usually is performed followed by a multi-week cooling to about 1200° C., in which the desired crystal is solidified from the melt. The single crystal so obtained is then cooled in a first slow cooling phase and then cooled to room temperature in a second accelerated cooling phase after the first cooling phase.
from https://patents.google.com/patent/US6364946B2/en