The groups are small and the unrest contained, but dissent is rising in this volatile Andean city, a barometer of frustration with nationwide shortages that are putting pressure on the socialist government of Nicolas Maduro.
Students, who also accuse the government of corruption and repression but whom Maduro labels "coupsters," are threatening to unleash larger demonstrations again.
"It's time," Deiby Jaimes, 21, said from behind a barricade of burning trash as police gazed down from their hilltop perch. "There's a social, economic and political crisis. Economically we're completely lost and in a delirium."
But Jaimes and other students said they were restraining themselves to see if other Venezuelans also take to the streets.
Last year's protests split the opposition and failed to attract widespread support from Venezuela's poor, meaning mainstream anti-government leaders like Henrique Capriles are calling for less radical tactics including peaceful rallies and a good showing at an upcoming parliamentary vote.
"People are scared," said Jaimes, an accounting student, as dozens around him knocked rocks together menacingly. "But fear is disappearing due to shortages. We're expecting a social explosion."
High demand and a Christmas lull in distribution have aggravated shortages across the nation of 30 million people. Queues sometimes snake around entire blocks, prompting isolated scuffles for coveted milk or diapers.
Although there has been scattered violence around the OPEC nation, many eyes are once again on the opposition hotbed of San Cristobal, where clusters of demonstrators have been facing off with security forces since the New Year.
It was here that the attempted rape of a student last year prompted protests that spread into a wave of national demonstrations.
Major General Efrain Velasco Lugo, who is in charge of security for the western Andean region, called the protesters misguided delinquents. "They want to torch the city again."
Their motto, he added, can be boiled down to "because I think differently to you, I'm going to topple you."
Indeed, Maduro says right-wing foes, encouraged by the United States and compliant foreign media, are plotting an "economic coup" to topple his socialist government. Protesters retort they are decrying flawed policies, like currency controls that have crimped imports and led to shortages.
Army officials said on Thursday 18 protesters had been arrested in San Cristobal, capital of Tachira state, in the last 10 days, with six currently behind bars.
Rights group Penal Forum said 56 demonstrators were arrested nationally this year, with most now released.