Mainly steel fences but the principle is the same, plenty of countries have barriered themselves off. It's a sad state of affairs that it has incresed rather than decreased recently.
Argentina-Paraguay Argentina Under construction N/A Anti-illegal immigration, anti-illegal trade and anti-drug smuggling
Belize-Guatemala Belize Proposed Disputed Territory and Anti-illegal immigration
Botswana/Zimbabwe Botswanaand Zimbabwe 2003 Anti-illegal immigration
Brunei/Limbang Brunei and Limbang 2005 Anti-illegal immigration
Bulgaria/Turkey Bulgaria 2014 Anti-illegal immigration
Ceuta border fence Spain 2001 Anti-illegal immigration
China/Hong Kong Hong Kong 1960s -early Anti-illegal immigration
Costa Rica/Nicaragua Costa Rica Proposed Anti-illegal immigration
Chinese-Korean border fence China and North Korea Under construction Anti-illegal immigration
Egypt-Gaza barrier Egypt 1979, subterranean barrier under construction Anti-terrorism and anti-illegal immigration
Estonia-Russia border fence Estonia and Russia Planned anti-Russian intrusion, anti-illegal trade and anti-illegal immigration
Macedonia-Greece barrier Macedonia 2015 Anti-illegal immigration
Malaysia-Thailand border Thailand and Malaysia Proposed Anti-terrorism
Melilla border fence Spain 1998 Anti-illegal immigration
Hungary–Serbia barrier Hungary 2015 Anti-illegal immigration
Hungary–Croatia barrier Hungary 2015 Anti-illegal immigration
Indo-Bangladeshi barrier India Under construction Anti-illegal immigration
Indo-Burma barrier India Under construction Anti-drug smuggling and anti-terrorism
Indian Kashmir barrier India 2004 Anti-terrorism (disputed territory)
Iran-Pakistan barrier Iran and Pakistan Under construction Anti-drug smuggling
Kazakh-Uzbekistan barrier Kazakhstanand Uzbekistan 2006 Anti-drug smuggling
Korean Demilitarized Zone North Koreaand South Korea 1953 Conflict zone
Kruger National Park South Africaand Mozambique 1975 Anti-illegal immigration
South Africa/Zimbabwe Border South Africa 2000s Anti-illegal immigration, Anti-drug Smuggling, Anti Weapon Smuggling
Pakistan-Afghanistan barrier Pakistan Proposed Anti-terrorism
Saudi-Yemen barrier Saudi Arabiaand Yemen 2004 Anti-illegal immigration
Saudi-Iraq barrier Saudi Arabiaand Iraq 2014 Anti-illegal immigration and Conflict zone
Slovenia-Croatia barrier Slovenia under construction Anti-illegal immigration
Turkmen-Uzbekistan barrier Turkmenistanand Uzbekistan 2001 Anti-illegal immigration
Ukraine-Russia barrier Ukraine and Russia Under construction Anti Weapon Smuggling and Conflict zone
United Arab Emirates-Oman barrier United Arab Emirates and Oman Under construction Anti-illegal immigration
United States–Mexico barrier United States Under construction Anti-illegal immigration and drug smuggling
Uzbek-Afghanistan barrier Uzbekistanand Afghanistan 2001 Anti-illegal immigration
Uzbek-Kyrgyzstan barrier Uzbekistanand Kyrgyzstan 1999