Tunguska, thanks for sharing "Preller's collection." I am not a Preller fan as he wrote some rather hard-to-believe articles about his involvement in moving the Kruger Miljoene.
Although difficult to see detail, below an identification effort of the depicted badges and buckles. Owen refers to non-sterling silver as white metal but that would be giving-in to British snobbery and since this pertains to Boer stuff we can call it silver. With the exception of perhaps 1, 3, 7, 14 19, 26 and 31 all items shown are rare or very rare.
1: Brass or silver ZAR Police helmet plate pre 1901 (Owen 2007 or 2008)
2: Silver ZAR Artillery cap badge pre 1901 (O 2004)
3: Possibly: silver ZAR Civilian service lapel badge (O 2023)
4: Brass State-Artillery Officers Sabretache badge pre 1901
5: Silver Helmet badge worn by Native Police ((O 1992)
6: Brass ZAR Artillery cap badge pre 1901 (O 2006)
7: Brass ZAR Police Martingale badge pre 1901 (O 2010)
8: unidentified Silver ZAR State Artillery cap badge (position of “maakt” is unusual)
9: Silver Vrijwilliger cavalry corps badge (Krugersdorp, Pretoria or Ermelo) (O 2040, 41 or 42)
10: Brass ZAR horse bridle rosette, also used by Mounted ZARPs (O 2031)
11: ?
12: Possibly: Silver Johannesburg Vrijwilligers slouch hat badge 1893/1899 (O 2043)
13: ?
14: ZAR pouch badge pre 1902 also worn on Filed Service Helmet. ( O 1994)
15: ZAR pouch badge pr 1902 (O 1996)
16: ZAR pouch badge pre 1902 also worn on Filed Service Helmet. ( O 1994)
17: Brass ZAR Artillery single or double shaft type helmet plate pre 1901 (O 2002 or 03)
18: Possibly: ZAR horse breast-plate badge (O 1989)
19: Brass ZAR police waist belt buckle pre 1901 (O 2057)
20: ?
21: Silver or brass ZAR officers helmet plate pre 1902 (O 1988 or 1993)
22:Possibly: belt buckle (not in Owen)
23: Possibly: variation on Brass ZAR horse bridle rosette (not in Owen)
24: Brass ZAR Horse bridle badge pre 1901 (O 2013)
25: Silver ZAR variation on Sate Artillery Cap Badge (O 2022)
26:Brass ZAR Police Martingale badge (O 2012)
27: Silver ZAR variation on Sate Artillery Cap Badge (O 2022)
28: Variation on Brass waist belt buckle identified by MC Heunis as worn by Pretoria Volunteer Korps see earlier post by Neville. (Not in Owen)
29: Silver ZAR Police helmet plate (probably worn around 1881) (O 2014)
30: cast? Brass ZAR Martingale badge (O 2005)
31 Silver ZAR State Artillery cap badge (O, 2016, 2017 or 2019)
32: Silver ZAR State Artillery cap badge (O 2020)
33: ?
34: Silver ZAR Police helmet plate pre 1901 (O 1998)
35: Brass ZAR State Artillery Other Ranks Sabretache badge (O 2035)